The ZX Spectrum conversion of the Data East arcade game, Karnov, is a good example of a decent arcade conversion on the Spectrum.

The graphics are colourful, well-drawn, and avoid colour clash by using a black masking effect around the sprites. It’s quite a clever technique that works very well in this game.

Gameplay-wise: Karnov is an unforgiving arcade game, and this Spectrum conversion is marginally easier than its parent, helped in a perverse way by the frequent slowdown. It’s reasonable fun though and worth digging out if you like challenging platformers.

More: Karnov on Wikipedia