Research large Projects

Game Dev Tycoon
#1

I think that I messed something up.
I can’t research large projects. Whats the requirement to develop large projects?

In particular: I am in the largest building, but working with the 3D engine V5 in medium project won’t make that much sense.

Thanks

#2

It unlocked for me as soon as I hired a 5th person. I don’t know if there are other requirements though. Maybe cash and/or fans.