Scorch - Atari 8-bit Scorched Earth clone source code

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Scorch is a multi-player, turn-based, artillery video game. Tanks do turn-based battle in two-dimensional terrain, with each player adjusting the angle and power of their tank turret before each shot.

by Tomasz 'Pecus' Pecko and Pawel 'pirx' Kalinowski

Warsaw, Miami 2000, 2001, 2002, 2003, 2009, 2012, 2013, 2022

Contributors:

• Kaz - splash screen, ideas
• Miker (@mikerro) - game sfx, ideas, QA
• Adam (@6502adam) - font, ideas, QA
• Bocianu (@bocianu) - important ideas, FujiNet implementation, QA
• Emkay - splash screen music

QA: Probabilitydragon, KrzysRog, Beeblebrox, EnderDude, lopezpb, Dracon, brad-colbert

You can contact us at pecus@poczta.fm or pirx@5oft.pl

This source code was originally compiled under OMC65 crossassembler and on 2012-06-21 translated to mads.

Compilation: mads scorch.asm -o:scorch.xex

Game source code is split into 5+4 parts:

• scorch.asm is the main game code (with many assorted routines)
• grafproc.asm - graphics routines like line or circle
• textproc.asm - text routines like list of weapons and shop
• variables.asm - all non-zero page variables
• constants.asm - various tables of constants
• display.asm - display lists and text screen definitions
• ai.asm - artificial stupidity of computer opponents
• weapons.asm - general arsenal of tankies
• definitions.asm - label definitions, moved to make it work better with Altirra debug (it doesn't).

We were trying to use macros, pseudo-ops and simple graphics primitives as much as possible. This way it should be relatively easy to port this code to e.g. C64

After those N years of working on this piece of code we are sure it would be much wiser to write it in C, Action! or MadPascal but on the other hand it is so much fun to type 150 chars where all you want to have y=a*x+b :)

Originally most variables were in Polish, comments were sparse, but we wanted to release this piece of code to public. Because of being always short of time/energy (to finish the game) we decided it must go in 'English' to let other people work on it. It never happened, but we got some encouraging comments and we are still trying to do something from time to time.

With the advent of fujinet (https://fujinet.online/) we are thinking about making the game interplanetary, err, with multiplayer over the net. We'll see.

Changes:

Build 141

2022-05-22 Debug build. Thanks to all testers for finding numerous bugs. We tried to fix some of them and we have introduced some new for your enjoyment.

• https://github.com/pkali/scorch_src/issues/73 Fast forward. Press [START] to speed up the game where it can be sped up. Not in many places, mind you.
• https://github.com/pkali/scorch_src/issues/72 Screen glitches improved
• https://github.com/pkali/scorch_src/issues/70 AI shoot with more force than their energy allows. We might still have to revise this one
• https://github.com/pkali/scorch_src/issues/69 Explosions wrapping around the screen
• https://github.com/pkali/scorch_src/issues/67 Screen glitches after intro
• https://github.com/pkali/scorch_src/issues/65 Saved ~90 bytes by removing cosinus table
• https://github.com/pkali/scorch_src/issues/62 Empty list of defensive weapons gets corrupted. Plunged it with a new defensive weapon - "White Flag". Honor of the tank crew prohibits them from buying it (yet)
• https://github.com/pkali/scorch_src/issues/61 [SHIFT] was repeating the last key
• https://github.com/pkali/scorch_src/issues/57 Fire too sensitive on a real machine. Switched to shadow registers. First recorded use of Atari OS :O
• https://github.com/pkali/scorch_src/issues/55 Glitches in the status bar. This one was surprisingly tough.

Build 140

2022-05-15 Huge internal changes by @Pecusx. The whole game screen has been inverted - ground is now background color, "sky" and empty areas are in fact pixels. This allowed for introducing better tank colorization, fully devised and lead by Adam. The process started and results are already promising - the colors of tanks and the status bar are closer. We might get even better ones in the next builds.

• few new sfx added (end of round, weapon change, soil eating weapons)
• added colors to tank name and level selection screen
• Bug https://github.com/pkali/scorch_src/issues/57 possibly alleviated by using TRIG0S instead of TRIG0. Please test - it did not show for me. Other unlisted minor bugs and typos fixed. "Nightly" version moved to develop branch. master will be updated with stablish and playablish builds only.

Build 139

2022-05-09 The post midnight release with great, heavy new features:

• https://github.com/pkali/scorch_src/issues/48, https://github.com/pkali/scorch_src/issues/10 - thanks to @mikerro we have a bunch of fresh sound effects. Not everything is perfectly implemented, but the game definitely got nicer! Thank you again Miker!
• https://github.com/pkali/scorch_src/issues/42 New weapon - Liquid Dirt by Pecus. Try it from directly from the weapon store!
• (fix) https://github.com/pkali/scorch_src/issues/53 - non-existing weapons are not displayed. This makes the defense menu empty when you are poor, but it is still better than the old way with "$0" prices
• (fix) https://github.com/pkali/scorch_src/issues/49 - seppuku should always kill now

Build 138

2022-05-02

• new version of font from Adam
• 80's style background gradient
• roller procedure refactored in preparation to liquid dirt

Build 137

2022-04-29 Premature release due to a trip to Atlanta on weekend.

• https://github.com/pkali/scorch_src/issues/41 Make Riot Charge and Riot Blast weapons. YAY a new weapon after so many years! And it is really useful when you get covered by a ton of dirt
• land-slide optimization by @Pecusx: ~400 bytes and some cycles saved!
• nicer explosions (say that to the target)
• improved wait macro to be non-blocking (moving towards asynchronous code :)))
• various memory optimizations - over 9KiB free RAM for further use!

Build 136

2022-04-24 This is a very important release because we had a chance to work a bit as an original team (Pecus and pirx). Let's cheer for Pecus for joining the task force again! Changes:

• another sneaky memory corrupting bug found and fixed. The game seems to be as stable as an Ikea table! No bug number because it was super elusive.
• MIRV loops https://github.com/pkali/scorch_src/issues/6 - a very interesting one. It happened when MIRV killed tank exploded with LeapFrog or FunkyBomb.
• Nicer font https://github.com/pkali/scorch_src/issues/37 - Thank you Adam for dugging up the font you made in 2008 :)
• Explosions are 2 times faster and look equally good or maybe even a bit better. This was a drag because of the Death's Head
• Memory map reorganized to extract some free RAM. Currentish map here: https://github.com/pkali/scorch_src/wiki
• Adam shared an archive that preserved a couple of the old build comments! Added below.

Build 135

2022-04-17 Happy Easter! This is a "premature ejacu.." err... "premature optimization" build. I got into an optimization fewer and got the code messed up, having to revert to the base. One important ticket closed:

• https://github.com/pkali/scorch_src/issues/35 Two morons shooting each other for more than 5 minutes. Added a new option "Seppuku". It causes one of the tanks ashamed with their inefficiency to detonate the weapon on itself. This was quite a difficult addition, requiring me to understand large swaths of the code, always a great challenge. Smoother gameplay with AIs guaranteed or money back. Other small fixes:
• https://github.com/pkali/scorch_src/issues/23 High flying MIRV leaves traces. Not anymore.
• https://github.com/pkali/scorch_src/issues/12 Make soil fall down faster after soil eating weapons. Soil eating range is OK, it is the soil down routine that is slow (but visually attractive).

Build 134

2022-04-10

• https://github.com/pkali/scorch_src/issues/34 - plot pointer visible only when missile is out of the screen
• https://github.com/pkali/scorch_src/issues/33 - Poor AIs do not purchase non-working weapons
• https://github.com/pkali/scorch_src/issues/32 - Basic is turned off right on the beginning of loading. Dracon reported problems with running the game in Altirra, this was the best idea I had about it. Maybe next will be removing LZSS routine by @dmsc from zero page
• https://github.com/pkali/scorch_src/issues/31 - STA WSYNC removed from missile flight delay
• https://github.com/pkali/scorch_src/issues/30 - player level remembered between rounds, thx @KrzysRog
• https://github.com/pkali/scorch_src/issues/5 - funkybomb smoke stays on the edges of the screen

Build 133

2022-04-03

• bug: https://github.com/pkali/scorch_src/issues/7 tank stands on a single pixel spike. WhereToSlideTable vastly improved.
• enhancement: https://github.com/pkali/scorch_src/issues/15 Add player colors to purchase screen. Still room to improvement!
• enhancement: https://github.com/pkali/scorch_src/issues/22 Redesign information panel (top 2 lines of the game screen). Now game might make some sense for a newcomer :)
• change: https://github.com/pkali/scorch_src/issues/28 remove white lines around out-of-the-screen point tracker. Now it is visible and looks better!
• enhancement: https://github.com/pkali/scorch_src/issues/25 Missiles are too fast. Thanks @bocianu and @mikerro for the hint. Speed of the shell is configurable now, 5 speeds available.
• enhancement: https://github.com/pkali/scorch_src/issues/27 Remember game settings between games.
• enhancement: https://github.com/pkali/scorch_src/issues/24 Remember player names between games. Thanks @bocianu

Build 132

2022-03-27

• fixed bug: https://github.com/pkali/scorch_src/issues/21 Wrong number of shells purchased
• fixed bug: https://github.com/pkali/scorch_src/issues/19 Inventory not cleared on next match. When fixing in a general way (cleaning all variables on game restart) I encountered a very old and nasty bug that made the game running basically by pure chance.
• fixed bug: https://github.com/pkali/scorch_src/issues/18 selecting players using fire sometimes selects more than one. Rewritten keyboard handling to prepare for enhancements like #17
• tables of constants moved to a separate file, variables declared with .DS directive in preparation for memory map optimization.

Build 131

2022-03-20

• fixed bug: https://github.com/pkali/scorch_src/issues/4 It was really hard one, because I had to unspaghetti our own lousy code :]
• it is now impossible to purchase non-existing weapons.
• numerous edits / optimizations during debugging process
• bug tracker moved to https://github.com/pkali/scorch_src/issues

Build 130

2022-03-13

• fixed bug: Decreasing of number of bullets after a shoot does not work correctly. It does look like it is fixed, although all I did was moving decreasing before shooting. Displaying number of bullets immediately after shoot.
• fixed a very difficult bug - game was crashing from time to time, with corrupted code and/or screen. It was digger digging lower and lower, finally digging through the code. Right now the game is not crashing on me.

Build 129

2022-03-06

• added tune by emkay, lzss player by dmsc
• fixed bug "When result in points is >99 then only 2 first digits are displayed"

Build 128

2022-02-19

• fixed a bug making it harder to select AI level, unfortunately now player names can not include hyphen
• fixed numerous mistakes in handling bytes and words - possibly some of the crashes eliminated
• adw addr #1 --> inw addr. 200 bytes shorter code (and maybe very slightly faster)

Build 127

2022-02-14

• option to select number of rounds in a game
• rudimentary game over message (in results screen)
• game restarts

Build 126

2022-01-30

• fixed bug 006 (After some attacks the OffensiveText stays on the screen)
• fixed bug 015 (Only first shoot of FunkyBomb is correct
• fixed bug 016 (No falling soil after leapfrog)

Build 125

2022-01-23

• included splash screen by KAZ

Build 124

2013-12-21

• removed large chunk of redundant 4x4 print code and table generation code, over 1kb gained.
• plot and point routines speeded up by ~20 cycles :P (and shortened by few bytes as well)
• fixed bug 011. High flying bullets sometimes cause brief screen garbage - like a DL damaged fixed by plotpointer (the top line) changed from HSCROLL based to regular $f line with plot
• screen memory moved to low area ($1010), making the game start at $3010 and easier to be loaded. Other minor memory layout modifications.

Build 123

2013-12-10

• fixed bug 013: sometimes demo mode does not work (it stops on results display)
• fixed bug 012: (newly introduced) Death explosions are offset right and possibly up.
• prepared the game for various screen width. The only problem is memory layout. Basically it is impossible to make contiguous wide screen of more than 170 lines. Changing the screen to non-contiguous would require rewrite of all character manipulating routines.
• fixed bug 014: FunkyBomb shoots with too high angle, funkyBomb angle changed from -8..+8 to -16..+16
• speeded up explosions by drawing only odd circles. Not bad visually and 2x faster.

Build 122

2013-11-17

• tank expend 1 energy with each shoot to avoid endless shooting loops
• small visual glitch with background colour fixed
• death messages "defensive texts" in source do not stay on screen after some explosions

Build 121

2013-11-10

• Poolshark and Shooter can buy weapons
• Purchase screen moved to the beginning of the round

Build 120

2013-11-09 SillyVenture 2K13 joint effort to bring artificial intelligence into life:

• Shooter and Poolshark shooting programmed
• several small bugfixes and improvements as proposed by SillyVenture crowd

Build 119

2012-06-17 Scorch sources translated to MADS with the sweet repl.sh script.

MISSING UPDATE INFORMATION... POSSIBLY NOTHING IMPORTANT HAPPENED HERE.

Build 115

2009-08-25

• fixed bug 001 (lack of explosions on the empty ground)
• fixed bug 003 (wrapping death's head explosions)
• fixed plot (faster explosions)
• fokk, just 6 years and we are back!!! This game is pretty addictive :)

TO DO:

• send our wives and kids away much more often :))))

Build 114

2003-08-22

• Results after each round are displayed in the right sequence, i.e. the best one is on the top
• during second and following rounds shooting sequence is such that the worst tank shoots first

The above changes does not look terrific, but there was a lot of thinking to do it correctly. What is the most important the overall game feeling improved a lot!

program.s65

• added routine SortSequence

textproc.s65

• changed routine DisplayResults to show round results in correct order

Build 113

2003-08-17 Again you dear reader made us to do a significant improvement in Atari 8-bit Scorch. Build 113 released! There is a framework for AI ready and you can play with the most stupid opponent - the Mighty Moron!!! Give him a kick and play a little bit!

• AI Opponents move barrels to the right position before firing a bullet.
• Purchase screen is not displayed for AI opponents.
• There is a 2 sec delay after displaying "Defensive" text i.e. text before death

program.s65

• added routine MoveBarrelToNewPosition which rotates barrel of the tank until it sits at the right (newly randomized) angle

textproc.s65

• added routine PurchaseAI it is a framework for all AI purchases

SHORTSYS.S65

• new macro PAUSE (waits given number of frames)

Build 112

2003-08-15

First attempts to create a framework for intelligent opponents (AI). Right now there is only one level of "intelligence" - Moron.

Moron shoots at random angle with random force.

program.s65

• routine Round checks the Skill level and if it is not human branches to ArtificialIntelligence routine.
• new routines:
  • ArtificialIntelligence
  • RandomizeForce
  • RandomizeAngle

TO DO:

• nice rotating barrel of AI tank
• AI weapon purchase and usage
• AI better than Moronic... (but how...)
• tanks' shooting sequence should be from weakest to the strongest, not random

Build 111

2003-07-27

program.s65:

• added sequential shooting (not necessarily tank no. 1 shoots first)
• added routine "RandomizeSequence" that is called before each round
• initial angle of the tank's barrel is randomized (was always 45 degrees right)

variables.s65

• added table "TankSequence"

grafproc.s65

• shorter delay during Flight

Build 110

2003-07-21 Previous release was a mistake. Build 110 is more or less playable, the "only" problem for now is such: in every round there is the same sequence of shooting (1st, 2nd, 3rd tank and so on). It should be like the weakest tank shoots first.

Build 103

2003-07-09 For the first time Scorched Earth for Atari XL/XE (build 103) published. Together with Pecus we were working on this piece of code for four years and it does not look like it is accelerating so we decided to publish what we have. Last few weeks I was translating source code comments and labels to English to let other people work on this project with us. In other words Scorched Earth becomes an open source project :) Now it's your turn to help this idea happen!

...transmission error...former history missing...