Anyone interested in trying a mod? I made one a couple of years ago for computer science class. It is a survival mod with a ridiculously long intro (that can be turned off). It's lacking a bit of polish, but plenty playable, and features achievements, random wave generation, and in-level upgrades (not menu based, but stage based, and you get energy/weapon restores at random in between waves). The only thing with it is it's harder to launch on the Steam version, because the last time I tried it the game would not receive command line arguments. But I can work around that. Anyone interested?
Update: I've bundled and uploaded the mod. This is the original version + training menu override for launching. There are two versions: one with the intro (which is around 10 mins long), and one without.
With intro: http://www.mediafire.com/file/221dsxcysreubh8/gm-survival.dpk
Without intro: http://www.mediafire.com/file/uls6q9dqvlh8v00/gm-survival_introskipped.dpk
Download the one you want, and rename the file to "data_a.dpk". Drop it into your Project Freedom installation folder, in the same one that contains "data.dpk". Open up Project Freedom, select Training, and click Start Mission.
The preview screenshot is just a placeholder. There are no container ships in this mod (because they require scripting in a proprietary format). I'll update the preview shot in the next release.