Add parts of
Support_LegacyDoors Expanded into default legacy doors (probably only the ghost brick fix)
Add the tab shifting brick selector gui addon
Add the resizable brick menu with some edits
Open up more colorset stuff to modders. Being able to mess with the colorset stuff and especially add the ability to add more enteries to the fx list would be nice. There needs to be a water FX option. Perhaps I could also try to optimise the amount of datablocks needed for a large colorset. By doing that, I can increase the maximum colors allowed in a colorset. I'd also want to fix the bug that hides some fx color options if you have a really short colorset.
Probably find some bits I could try to open up or make easier for modders to mess with. (relates to colorset stuff above)
This is all assuming I'd have access to absolutely everything and that I knew what I was doing. If this were to actually happen It'd probably result in a broken mess like my older deathmatch and fastkarts gamemode versions. Also again, I'd be limited to a week.