I always liked Red Alert 1 and I would like it if Skirmish mode was 100% redone like being able to pick where you spawn, and to allie with the AI. And would love to see the AI be optimized for the mod!
Also is it possible to include all the country's instead of just Allies and Soviets? Since each one had a country bonus in RA1 it would be cool here.
A bit off topic but it would be cool (but funny) if each country changed your soldier's accent (imagine playing as the French XD)
P.S: I never played SC2 so I am not sure what it can/cannot do other then the naval I read from you.
EDIT: I know you probably thought about it by now but you can add the CTF mode and maybe add the Mobile HQ mode from C&C95 which is basically a bases off mode with a small twist, you must defend the Mobile HQ that you are inside! If it dies everything you own blows up and instantly lose the match. Red Alert reused the HQ for it's Mobile Radar Jammer.