What are your hidden coop games?

This may be a weird question but what games have you enjoyed playing coop that aren't necessarily in the spotlight? I've played loads of Mario and Luigis mansion etc. Etc. But im talking about something different than that. My example is Borderlands 2. Did you know you could split screen? I'm looking for alternatives to the regular platformer formula we see over and over and OVER until the end of time. Ideas? Also not to put aside anyone's favorites but the top 20 lists all have the same games, hit me with something creative!