Author Topic: Donkey Kong - Kong League Championship - rom-hack  (Read 5369 times)

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Offline PaulGoes

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Donkey Kong - Kong League Championship - rom-hack
« on: March 01, 2020, 06:53:34 am »
A few weeks ago WFLIMusic asked me if I could create a Kong League Championship edition of Donkey Kong. The idea was to have a Donkey Kong version with a shorter gameplay by introducing the famous Kill Screen at an earlier level. This version could be used in one-on-one or head-to-head games and tournaments.

I loved the idea and created a quick prototype to test if it is possible to recreate/simulate the integer buffer overflow that causes the Kill Screen. After ten minutes I was able to make the game to Kill Screen at any level that I configured (even on level 1, although this is obviously not very useful!).

The past two weeks I turned the prototype into a useable rom-hack: Donkey Kong - Kong League Championship.



The game defaults to a Kill Screen at level 11. But this is configurable using the dip switches that normally control the bonus life threshold. The bonus life threshold is now fixed at 7000. The following dip switch settings control the Kill Screen level:

  • Dip switches - 00 - Kill Screen at level 11 (originally bonus life at 7000)
  • Dip switches - 01 - Kill Screen at level 09 (originally bonus life at 10000)
  • Dip switches - 10 - Kill Screen at level 07 (originally bonus life at 15000)
  • Dip switches - 11 - Kill Screen at level 05 (originally bonus life at 20000)

The selected Kill Screen level is shown in the level progress screen:



As an extra the game detects it when the player loses his/her last life because of the Kill Screen. Then it doesn't display the normal 'GAME OVER' message but displays a 'KILL SCREEN REACHED' message instead and plays an accompanying melody.



As you can see I also branded the game as 'Kong League':
  • Instead of the text 'HIGH SCORE' at the top of the screen it shows 'KONG LEAGUE';
  • The Goofy Kong at the level progress screen holds a sign that displays the Kong League logo.

One additional thing. During the design I restricted myself to the following constraints:
  • Use the orginal dkong rom (US version). This meant that I only had around 160 bytes of free space to put my changes in. Quite a challenge I must say!
  • Do not change anything in the core gameplay logic. This was possible because the bonus timer is calculated before the level/screen starts to play so the required change doesn't impact the gameplay itself.

I playtested the rom-hack and am confident that I reached a version that is playable and ready to release to you. So attached you find the dkong.zip for the v1.00 of this rom-hack.



The working patch is available for download in the KL Discord https://discord.gg/VqwmtBe.



« Last Edit: March 04, 2020, 12:25:36 pm by wflimusic »
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Offline hooch66

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #1 on: March 04, 2020, 06:28:41 am »
This is a really cool idea and well done!
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Offline Mitch Mitchell

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #2 on: March 04, 2020, 12:31:20 pm »
Fantastic job, like a lightning round competition version; very cool.
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Offline Mitch Mitchell

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #3 on: March 04, 2020, 12:42:53 pm »
Spent 10mins or so searching for rom download on that discord you linked to no avail; can you post a direct link?
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Offline NWnike

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #4 on: March 04, 2020, 01:55:12 pm »
Mitch, the DL link has been taken down temporarily in the Kong League Discord. It will be available again soon. Hang around in the Discord and it will be announced when it's ready for DL.
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Offline Mitch Mitchell

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #5 on: March 04, 2020, 07:06:14 pm »
Thanks appreciate the heads up.
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Offline NWnike

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #6 on: March 06, 2020, 06:45:10 pm »
Mitch, there is a working link for the new ROM patch now in the discord server.
« Last Edit: March 06, 2020, 09:19:06 pm by wflimusic »
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Offline Robert

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Re: Donkey Kong - Kong League Championship - rom-hack
« Reply #7 on: March 07, 2020, 01:15:41 am »
Thanks!  :)
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