The list could do with a
Puzzle section:
Enigma, a free clone of the German shareware game Oxyd (1990), also known on the Mac, Atari ST and Amiga.
Pingus, a free Lemmings clone for Windows.
Pragmatica, a 'logic, prediction and programming-based puzzle game', might also appeal to fans of SpaceChem.
Pushover remake by Ishisoft.
Fetus & suteF (already on the list, filed under Action etc.) would also fit in a new puzzle category.
Platformers would deserve their own separate category, too:
Frozzd. From the game description: "Jump from planet to planet as you guide the Mubbly creatures, and use them as an army to defeat the Frozzd. 12 levels, a boss, many different enemies, and great music."
Approaching Dawn, another nice Platformer, in style a bit reminiscent of Knytt.
Eternal Daughter by Derek Yu. Story-oriented oldschool platformer with great pixel graphic (scroll to the bottom of the download page).
Some games already on the list that would fit the category: Cave Story, Ikachan, Knytt, Secret Maryo Chronicles, Sonic Fan Remix, Spelunky, The Goonies ...
Last but not least another recommendation for
Adventure fans:
The Marionette, a short first person point-and-click adventure with a horror theme, beautifully painted.