Those looking to recreate the X-Com experience but unable to get hold of the original games for whatever reason may be interested to know that Rebelstar: Tactical Command is available for the Gameboy Advance and features similar gameplay, although without, AFAIK, the resource management.
In addition, X-Com was the ultimate development of an earlier series of similar games beginning with the 8-bit Rebelstar, Rebelstar II and Laser Squad, all of which can be emulated. Laser Squad introduced many elements that made it into X-Com, including limited resource management and collateral damage, and is still very playable today. Versions are available for Amstrad, Atari ST and Amiga, but true Raiders will opt for the ZX Spectrum version.