Part three of rule four seems to say this:

Third Party resources are exempt from this rule as long as they are also available for usage/purchase by other participants.

What counts as “third-party resources” here?

My first thought was it would mean “made by someone else”. Under the first definition, it would mean I can use Ren’Py, Unity, Naninvel, Tyranobuilder, Godot, Unreal Engine and Visual Novel Machinery, but not Basket Letter Vibe since I made the latter myself before the jam (and released it under the MIT license; well, I’ll be happy if I see other Godot users using it to add accessbility features to their VNs, Godot VNs usually seem to have interesting mechanics or animations, so combining that with Ren’Py-like accessibility tools would be nice). It also means people who have contributed to open-source engines in the past would probably not be allowed to use those engines other than using older versions from before their contributions. So that would benefit people who haven’t made anything for others to use, while it would make things harder for engine developers, who would then have to use each other’s engines. So would that be good or bad?

• Since engine developers know their own engines really well, probably better than others, I suppose it makes sense to restrict them in some way, but I’m not sure how much they should be restricted.
• We also have general-purpose knowledge about things like programming languages, which we might be able to use even when using another engine.
• Someone could have advanced knowledge of an engine without being one of its developers, in which case they’d still be allowed to use that engine.
• People who spend money on things others can’t afford would still have an advantage over those who can’t afford the same resources.

But I’ve also seen discussion on the DevTalk Discord server suggesting it would mean “not made specifically for one team”. In that case, as long as it was published before the jam under a license that would let any team use it (especially if it was available for free; otherwise the developers would have to “pay themselves” to be able to use their own tools).

Also, I assume “resources” means stuff used in the game itself. If things like written-down knowledge about the real world (like researching a historical period to write about events set in that period) might cause issues.

For now I’ll probably make my prototype in Godot and initially use Basket Letter Vibe, but not work on the minigame until I know whether I can use that. That way, if I get told not to use BLV, I can switch to Ren’Py more or less easily (the minigame would be the hardest thing to convert between engines).