Cheat Code Central
- Includes instructions for entering hidden modes, and Game Shark codes.
- http://www.cheatcc.com/psx2/hi.html

All Game Guide
- Review by Scott Alan Marriott. "Hidden Invasion tries to tie together The X-Files with something along the lines of Red Dawn but ends up being yet another boring 3D beat-'em-up that offers nothing new to the genre and everything wrong with it."
- http://www.allgame.com/cg/agg.dll?p=agg&SQL=GRH||||35578