This is not very difficult. The design constraints of each are fairly unique. A few good heuristics:

- Windows: Few or many? Are they only on the top floor? Are they small? (Prisons don't have lots of windows.)

- Bars on windows? (Dead giveaway for a prison.)

- Lots of security cameras? (Not the best indicator, but it weights in favor of prison.)

- Fences around parking lots? (Criminals might want to break into cars.)

- Is the name on the building large, inviting, and stylish? (School.)

I think the message being sent is more interesting than the "game".