Okay, we'll I'm sure we all miss funday monday asmuch as I do and so wanted to spit ball some ideas that maybe Day could see and use.
A few ideas to start things off are as follows...:
As Protoss you can only power buildings via Artosis. So 1 pylon per 3 buildings. For supply you can build a mass of pylons as long as 2 pylons do not power the same building! (that is semi easy)
As Zerg you cannot build any spine crawlers or mutalisks. (Idea for this one is that it is harder to defend and do late Broodlord Infestor pushes with the spines and makes zerg wanna try kill opponents earlier. The no mutas is because you almost do not need spines if you have a lot of muta for map control or harass or muta-ling-baneling.)
As terran you are not allowed to expand until you have 3 planetary fortresses NOT at any mineral patches.
Post more ideas down here and sorry for the bad ideas I had.
Have fun thinking some up!