Everything is so cheap after Christmas. I mean, look what you can get for FREE! :-)
The FreeOrion project just released version 0.3.11, which comes with some polish of existing features and a few small new ones. Here's the announcement. Only a Windows binary is up at the moment, bah, source only from SVN. I complained. (I'm good at that.) There are statically compiled SVN binaries for Linux but you have to go digging to find them. Still, when digging you can find treasure, like this ship development thread. Purty!
UPDATE: here's the Linux binaries and here's a quick play guide - which you really do need, there's so many clicky thingamajigs.
Platinum Arts Sandbox, the game design tool based on the Cube 2 engine, saw version 2.3 released a few days ago. From the announcement:
Here are the awesome new features!
* New 3D sidescroller Mario like mode! Also there is a seperate RPG project, check the wiki! [link - note it is aimed at kids and in concept stage]
* Hotkeys that make it easier to save games, add materials, and lots more!
* New in game help section that displays all of the binds/key commands!
* Snow has been tweaked and updated :) Be sure to check out the new version of house :D
* Maps now generate cfgs on save! Also many various map tweaks.
* New main menu theme! To try other themes check out the options menu.
* Loads of new textures and new player skins.
* Tons of under the hood bug fixes and features.
* Thanks to ZKAT of virtualdarkarts.net there is a brand new great looking launcher!
Here's one of the developers, Mike, talking about different aspects of developing Sandbox, along with gameplay clips. Quite interesting.
The DungeonHack team has been active lately and it is finally starting to pay dividends with a reorganized and improved codebase now coming back to life. Early days, still, so I'll leave it at that.
Vikings is an open-source RPG, presumably based on Vikings. This model of theirs is mighty nice!
Pyweek. It's one of those contradictory things in life. Some nearly-cool games get done in a short space of time, but then when those efforts can't be put into bigger and fuller versions of the concepts you see in Pygame is somewhat frustrating. Still, some nuggets in there like AFF:City, a city building game based on the Angels Fall First universe. If they can get that much done in a week, why not spend a few months on the game and it'll be awesome, surely?
A less serious but more mind-bending game is the imaginately titled 4D Maze Game. Play it online in an applet or browse the source. I didn't really conceptually understand how the maze works, thus I failed to escape after going in random directions in 4 dimensions for a few minutes. I hope I never get stuck in a real 4D maze, I'll be in real trouble!