Realistic-looking TPS, kinda like Duke Nukem Zero Hour.

Time frame? Timeless! Prequel, Middle, Sequel...even in the middle of the games!

Platform? PC of course. It wouldn't be Jazz then.

Multiplayer modes? Battle, CTF, Assault (team objective), and "User defined." "User Defined" can be used for multiple different things, such as Domination, Race, or free-run without the adaptation with other, unchangable game modes.

We should also get Rare to come do some of the things. I'm sure that the same technology used to make the excellent graphics of SFA would be perfect for a Jazz Jackrabbit game.

Other ideas: You forgot about the JCS. How are we to make things?