Secret ghost level for an indie gem

[MarkM]

Which indie gem would benefit most from a secret 'ghost level' that only unlocks after you beat the game in one sitting, and what would that level feel like?

[JonathanT]

Nice idea. Celeste would be perfect for a ghost level: beat it in one sitting and unlock a fever dream run with altered gravity, fewer checkpoints, and a surprise boss that teases what comes next.

[Sofia33]

That could work.