More hours were lost to UFO last night - I'm into April now, and the Snakemen have put in their first appearance. One of the nice things about UFO is the variety of enemies. You start off with Sectoids (the classic "Grey" alien), Floaters (who are as shit as their name would suggest), and the game gradually ramps up the difficulty, introducing Snakemen, who are tough, but slow, and eventually introducing Mutons (BIG Green Men) and the dastardly Ethereals, who, though physically weak, possess psionic abilities that can reduce grown men to gibbering wrecks - or worse, become mentally dominated and alien slaves - whom you have to stun or kill to prevent them wiping out your squad.
All of these races possess sub-races, or terrorist races, which all add to the fun. The terror races for the Sectoids and Ethereals are the nastiest of the lot, the Cyberdisks and Sectopods respectively, as they're evil robots with spookily accurate plasma weapons. However, the creepiest of these are the Chrysallids, who accompany the Snakemen. They're horrible insectoid chaps, who impregnate their victims, turning them into zombies, which transform into other Chrysallids if you shoot them, and also happen to be super quick and as tough as diamonds.
With this variety of enemies, the numerous terrain types, and the randomly generated maps, each tactical mission presents a unique challenge and keeps the game fresh. So whilst the visuals may have dated terribly, the actual experience of playing the game hasn't - it's as good as it ever was.
In the game, I've just finished researching the Psi-Lab and Psi-Amp, so I'm looking forward to waging Psi-War against the alien invaders in the next few game months.