I tumbled over these games while I was reading news from Steam, more precisely, rock, paper, shotgun -news and while I kept reading them I read about a challenge to make a game in 48 hours. So I went to the contest winners list and I played some of them and I think you should play at least these ones.
And here they are:
(You can download all the files by clicking the Windows link.)
Dare Islands:
http://www.ludumdare.com/compo/ludum-dare-17/?uid=117
Island Guns
http://www.ludumdare.com/compo/ludum-dare-17/?uid=1993
Radio Silence
http://www.ludumdare.com/compo/ludum-dare-17/?uid=80
Gaiadi
http://www.ludumdare.com/compo/ludum-dare-17/?uid=2037
Paradise Fort
http://www.ludumdare.com/compo/ludum-dare-17/?uid=491
The latest file for PF is here, and I recommend it: http://www.hempuli.com/PF.zip
And not in the 48 hours challenge but still...
Drone
http://dwwilson.info/?page_id=14
Also if you want to browse the contest entries here's the link: http://www.ludumdare.com/compo/ludum-dare-17/?action=top&cat=Overall&more=1