I was lucky enough to grow up on this system and there are some absolute bangers out there:

Mission: Shark (or Misja on the European continent): arguably one of the best games on the systems. Silky smooth animation, great gameplay loop, fantastic music. Janusz Pelc at his best.

Rescue on Fractalus: fantastic foray into faux-3D. You'll never forget the first time you picked up your first "pilot"...

H.E.R.O: finely balanced, a great time killer.

Encounter: far beyond it's years, the precursor to open world games

Fred: another J Pelc masterpiece. Great platformer.

Star Raiders II: beautiful shooter. The space shoot em' ups of today can trace their combat gameplay directly back here.

Lode Runner: one of the best and smoothest implementations of this game, along with...

Chuckie Egg: the original and best.

Zybex: a competent shooter with some of the best chiptunes you'll ever hear.

Blinky's Scary School: bastard hard, but full of British humour.

Fort Apocalypse: fantastic shooter, with stunning graphics and a blue doppelganger helicopter that will give you nightmares.

Rally Speedway: takes the top down racer formula, tightens the controls, makes it prettier, and gives you a level editor too. Brilliant.

River Rescue: River Raid but better, and if you disagree then you're entitled to your wrong opinion.

Have fun!