Code Tactics has updated their top-down homebrew airstrike game for the PSP (and Mac, Linux, and PC too). Apollonia v0.03 is said to be more of a maintenance release, and as far as the PSP goes, it's gotten some improved performance. And that's always a good thing. Here's the full changelog encompassing all platform versions:

* Added some new buildings.
* Improved performance on PSP.
* Improved particle engine.
* Fixed renderer to support OpenGL versions less that 2.0.
* Fixed crash in control screen.
* Fixed error in paths to resources in Linux.

The math involved in the game's code has been cleaned up for the PSP version, and with that improvement in place, they'd be able to put in cooler effects in the future versions.