This Korean developed mobile tower defense game is the only tower defense game that can be named "Tower Defense" since its developer owns the trademark to the term.
Defend the transport ship from being captured by enemy waves on the way to the jump hole. Upgrade weapons, kill enemies, get cargo, transfer cargo, buy features, repeat.
Starpires is a turn based, massive multiplayer, empire building/strategy game set in space. Battle other empires to move up the leader board and rule the galaxy.
A sci-fi action-strategy game released in Japan in 1986 for the NES, developed by T&E Soft and published by Toshiba EMI. It's part 6 of a long-running series, though the only one to be released on the NES.
UFO2 Extraterrestrials: Shadows over Earth is an upcoming real-time strategy / turn-based tactics game developed by Chaos Concept. It is the sequel to UFO: Extraterrestrials.