They're worth playing, but it's definitely not necessary. You may miss out on some of the callbacks and the finer points of the lore by skipping them, but otherwise you should be able to enjoy it just fine. I'd recommend looking into the story, though, because there's some fascinating stuff there.
Prizes are always welcome, just let me know what you want to give away and if you're doing raffle distribution or targeting a specific place (1st, 2nd, etc.)
I've got And Yet It Moves, Antichamber, Cities in Motion 2, Gunpoint, Little Inferno, Mafia 2, Monaco: What's Yours Is Mine, Solar 2, and 140. Might have more depending on what they add to the latest bundle on Tuesday. Can do a raffle to hand them out as participation prizes so that everyone gets something.