sibberke: It seems like a good bundle. The only game from those I have is Gemini Rue, so it could be worth it. I've always read that Defense Grid is a good game, as is Nuclear Dawn, but is that game played a lot (it is multiplayer, so this could be important). And could somebody tell me something more about the Soulcaster games?
The Soulcaster games are essentially "mobile" tower defense games, combined with minor puzzle elements. You control a wizard who can summon a fixed number of fighters, archers and bombardiers to whatever spot you move to, and they will stay in that spot until you summon them back to you or they die. If they die, they will return to you to and you can summon them again, but there's a small delay and monsters will hunt and corner your nearly defenseless wizard if you're on your own. Your wizard can move freely and you have to make your way through small levels, fighting off the attackers and reaching the exit by surviving all monster waves. There are also shops where you can spend money to upgrade your summoned allies. The games are comparatively short (I think the first Soulcaster can be completed in 1-2 hours?), but they are good games with a great soundtrack.