The ill-fated predecessor to Space Jam 2: Planetary Warp, Space Jam Demo is a bit more simplistic overall, but once you can get past that it's actually quite a bit more fulfilling than its sequel.

This game is a bit more linear-minded than its sequel; you mostly progress forward with the occasional boss. Be very careful about how you spend ammo (setting the MZX speed to 5 helps); the first boss will drain through it as fast as your health and lives. After several more levels, the game abruptly ends with an "END OF DEMO" message.

This game was never finished; according to the documentation in Space Jam 2, it was lost in a drive crash, which I find a shame, because I enjoyed it a bit. I think there's enough content here to net a second star, barely. Check it out if you like MZX platformers.