Two unfinished games by Nytar, with unique concepts for each of them.

Chameleon is a puzzle game in which you must shift between four colors to progress through different levels. Each color you shift to has a different weakness - for example, red will die if you step on a blue tile. The concept is realized here pretty well, with nice graphics.

The other game is Subdungeons, which only has one level, but gives a good idea of what the game's about. It's an overhead action-RPG, with the twist being that you can only carry one item in your hands at a time, and wear only one piece of equipment. So you must pick up armor with your hands, put it on, then take your power wand. If you wish to remove the armor, you have to drop the wand first. The game was designed for Speed 3, so it runs quite a bit smoother than other MZX games.

This is a pack worth checking out if you need inspiration for a game of your own, but for general gameplay purposes it's probably only a one-shot deal (as both demos are terribly short).