This is the INDIE STRATEGY BUNDLE currently on sale on steam. That is 5 games, including:

Anomaly: Warzone Earth--
Defense Grid: The Awakening--
Revenge of the Titans--
Sanctum--
Sol Survivor.--

I listed it as Defense Grid because SteamGifts doesn't seam to support promotional pack listing, and it was my favorite, though I have only played Defense Grid (my favorite) and Sanctum. I believe they are generally tower defense type games, with Anomaly being some reverse tower defense mechanics.

It is a single key, so you must take all 5 games, and steam will activate them all at once.

One other thing: This doesn't come with the Defense Grid DLC, but I highly recommend them if you enjoy the game. Defense Grid is probably the best retail tower defense (of its type) out there.

If you own one of the games, you can still enter! But just to let you know, steam will NOT give you extra copies (otherwise I wouldn't be posting 5 games since I don't own a few of them!)