Kim recommends...Exolon (ZX Spectrum)
Probably the best action game on the Speccy.
Out 'n' out action games on the ZX Spectrum tend to get a pretty bad rap, especially these days. Often, for most people, the games that are actually still worth playing on the system are...well, the more unique ones - things like Skool Daze, for example. However, there are definitely exceptions to the rule -- indeed, there's a fair few action games on the Speccy that are actually still very decent! And Exolon, from 1987, is one of the best of them.
Exolon has a very strong pedigree -- not only is it published by Hewson, who were responsible for a big chunk of the Speccy's best games (including Nebulus and Quazatron) but it was made by the excellent London-based programmer Raffaele Cecco. Cecco is responsible for a couple of games that you might know even if you don't have any Speccy experience -- Cybernoid, which was later ported to the NES, is one of his most celebrated. There's also Stormlord, which found a home on the Mega Drive thanks to Razorsoft.
Exolon isn't a flat-out action type game -- it's got a fair bit of puzzling in it too. Each level consists of a single screen, and several objects and enemies that you'll have to blow up in order to get to the end of the screen. You have a regular gun and also some homing grenades to do this with, both of which come in very handy, but the action does get considerably harder as the game goes on, with lots of tricky timing, teleportation, and projectiles to be avoided. If you're hit once by anything, then naturally you lose a life.
Like a lot of Hewson games, Exolon is also a very nice game to look at -- I'd go as far to say that it's probably the nicest looking Speccy game that I've recommended so far on here, with some big sprites and some very nice explosive effects for the system. It helps that it moves nice and smooth too, without much slowdown. It's perhaps understandable why, unlike Cybernoid, Exolon never managed to make it off of the computers -- it's flip-screen, and maybe that little bit too slow...still, it's excellent -- one of the Speccy's best, and simple enough that anyone can check it out and have fun with it. A great game from one of the Speccy's top programming stars.