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Jul 21, 2020, 02:21 AM
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Post GOG's Jazz 1.3: Fix bugs, add versions

Hi,

according to maxen7 in twitch chat, VioletCLM is considering to work with GOG about bugfixing GOG's Jazz 1. Thus: VioletCLM, is there something in the works here? I'll be happy to help where I can.

GOG distributes Jazz 1.3 and Holiday Hare 95. See my version comparison table.

Possible fixes for Jazz 1.3:
  • Fix the near-impassable Orbitus 2 bouncy section. The Jazz 1.3 executable (not the level file) enlarges the bouncy floor trigger areas. If GOG keeps 1.3 executable (reasonable), you can modify the level layout, e.g., with MaxStrike's patch. This adds solid golden bars to the underside of triggers that suck Jazz upwards. GOG users approve.
  • Fix the broken airboard ditches in Medivo 1, Turtemple 2, Pezrock 2. These are also bugs in the executable; the same level files produce working airboard ditches with a 1.0 executable and broken ditches with the 1.3 executable. Can these be fixed by changing the level files? I'm not knowledgeable enough in the Jazz 1 formats. At least Jazz 1.3 can ditch airboards in other levels successfully, e.g., in Battleships 1/2.
  • Binary-patch FILE0001.EXE to print a different version string during start than: Welcome to Jazz Jackrabbit. version 1.3 -- Reason: With above changes, it's not 1.3 anymore, and should not identify as such. The string sits in clear text in FILE0001.EXE, beginning at 0x3007. You can put anything that matches the original's length, e.g.: Welcome to Jazz Jackrabbit, v. GOG 0002
  • Ship an unmodified 1.3 as an extra. Reason: Third-party-patching their main version is a significant change and drops files from an unmodified 1.3. GOG prefers to ship several versions if they exist.
  • Ship an unmodified 1.0 as an extra. The 1.0 runs well right out of the box, all levels are passable. Jazz 1.0 is fastest for speedrunning Episodes 1-6: You can fit though Orbitus bouncy floor cracks, and 1.0's Dreempipes water lowers more slowly than the water in 1.2/1.3. GOG prefers to ship several versions if they exist.
  • Possibly ship an unmodified good 1.2; this has the longer Tubelectric 2 and thus adds content.
  • Maybe even ship a bad 1.2, purely for completeness.
  • Maybe even ship a 1.1, purely for completeness.
Any extra versions need not be selectable from GOG's launcher within DOSBox. 90 % of players won't want any choice, they want a version that works, where they won't get stuck in Orbitus 2. It's perfectly sufficient for GOG's menu to offer Jazz GOG 0002 and unmodified HH95.

For the remaining 10 % of players who care about the different versions, GOG can put the extra versions for manual extraction besides their main installation.

The airboard ditches in Medivo 1, Turtemple 2 and Pezrock 2 need most planning. Everything else has a solution that looks reasonable to me; still, any change is possibly intrusive and should be discussed.

I'd be happy to provide 1.0, the good 1.2, even the bad 1.2; the problem is that all the Jazzes are still copyright-restricted. GOG should prod Epic Megagames. I'm only a fallback source, and I'd need a written deal by GOG first. I don't have a 1.1.

-- Simon

Last edited by Simon; Jul 21, 2020 at 03:35 AM.