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Old 05 October 2011, 17:10   #1
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Kroah's Avatar
Join Date: Apr 2009
Location: France
Age: 43
Posts: 114
Hey all,

Two weeks ago, after the release of my Gods Viewer, i had a conversation with a friend about the feasibility of remaking a (not too big) Amiga/Atari game on Windows in less than 1 month, using my method of disassembling the games.

I should use the word "conversion" instead of "remaking" because the aim is to do an exact copy of the game on Windows, without improving it. Of course, we could still improve it after and port it to other systems if needed, but that's not the main objective.

By "conversion", i mean both games could be run side by side and they should have the exact same behavior, therefore the same displayed frames. This implies the game should not use any kind of clock based RNG (random number generator) but instead soft RNG algorithm.

To help the conversion process, 2 things are essential:
- A good knowledge of the game is needed to understand the disassembled game and the data structure. I want a comprehensible remake with some structured objects, NOT a blind conversion where each ASM line is converted one by one.
- The simultaneous and frame by frame run of both games helps a lot the debugging part. Being synced with the RNG, even the smallest bug have big consequences in the following frames. Correcting the bug and running the simulation again with the same RNG seed up to the previously bugged frame confirms or not if the bug has been correctly fixed.

Otherwise, there aren't any way to know that some parts are badly converted because they 'seem' behaving correctly (visually correct and no crash) but in fact are incorrect and behave differently from the original game, thus giving a different gameplay experience.

I want the game to have the exact same feeling and gameplay than the original game!

My Colonial Conquest remake and OpenTTD (Open Transport Tycoon Deluxe) are good examples of extended 1-1 conversion.

After this introduction, let's go to the game itself.
Being a fan of Bitmap Brother's game, my choice is Speedball 2. Yes, zenox98, you were right .

Right now, the game is disassembled and the match part is fully converted (jumping, tackling, AI, bonus, score multiplier, bouncers...).
The game runs exactly the same frames as the original one with the same RNG seed. There's no sound, and controls are really basic (no joypad support).

I still track some subtle bugs but I should release something soon.

I don't know if i will have enough time in the upcoming weeks to add the remaining parts (sound, training, league, cup, amiga gfx, etc).

I don't post any screenshot because it's the same as the original. So here's the field map with initial and ingame Team 1 location. You can see red zones used by the players to know where they should act.

Click image for larger version

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Edit 2011/10/07: WIP 01 released (read the thread)

Last edited by Kroah; 07 October 2011 at 03:09.
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