Not to brag but to review for anyone still shopping:

Dungeon Defenders + DLC
(Good game, manageable on old computers with the SSE fix, compatible with any game pad that can be mapped to keyboard. Newest mission DLC appears to overwrite default missions.)

Serious Sam Gold HD
(Awesome job done by Crave - offers enough backwards compatibility adjustment options to run on old systems. Now looks better than it did in the 90's even if not as HD uber as it would if I had a better computer)

Serious Sam Random Encounters
(worth the current sales price)

Serious Sam Double D
(Due to hidden executable Steam version is impossible to map to game pad - if purchased legitimately it isn't too difficult to locate the cracked version on the net which fixes the game pad problem. Awesome game once you get it work.)

APOX + Expansion
(Sloppy and abandoned by both developers and players - with excessive patience it is playable but so buggy that game play is not enjoyable)

Chantelise - A Tale of Two Sisters
(Completely compatible with old systems and game pads and absolutely charming)

Puzzle Quest 2
(Everyone knows what this is)

Tesla - The Weatherman
(Short and sweet - a much more functional and less frustrating clone of Doc Clock)

How long is it? Where'd you find it discounted? On my Steam wishlist it was still full price. Better or worse than Challenge of the Warlords?

I got it around its release and beat it about an hour or two after it installed. So, it's a short game, but it's really fun for the duration. And it has an Endless Mode, but I never tried it.

I absolutely loved the first one, the second one disappointed me greatly. The movement is annoying, the interface is clunky, the minigames are absurdly repetitive, as well as the combat, unfortunately - there's more emphasis on creating a character build and doing the same combos every fight. Snore.

Some people liked it though, so I dunno.

Only played about fifteen minutes of Random Encounters so far so can't really comment on the length other than to say that it could easily get repetitive and boring if it goes on for forty plus hours like the old RPGs that it is mimicking.

Also, played Challenge of the Warlords only on DS and DS the game is a lot different from the PC version.

You can find PQ2 on sale for $5 at GamersGate.

Not on sale but also picked up within the last week was

Explodemon!
(Old computer friendly and easy to map game pad to mouse and keyboard.
I'm enjoying it but controls have a higher learning curve to master than most platformers. Slight RPG element via purchasing upgrades from shop at the end of each level. Enough alternate paths and out of the way areas for gamers who like to explore. Ranking system ads even more replayability for speedruners. There appears to be three or four worlds with four levels each - levels are quite lengthy)