Megazeux (or MZX, as it's sometimes called) is a fairly powerful tool for creating and playing your very own games. Don't get the idea that you can make anything groundbreaking or incredible, since the graphics are basically just simple blocks and sprites. The sound is also pretty basic, consisting of beeps and blips. The best way to describe it is that it looks like something from the Colecovision days but anybody with a little time, some hard work, and a decent amount of commitment should be able to put together some fun little games.
This brings me to my next topic. The file is quite small and doesn't take up any space at all hardly, and naturally, it'll run on any older system you can find. If you've got an old laptop laying around or something, don't heave it off a bridge, instead, give Megazeux a go. The most important thing to remember though, is that when you first begin, things will seem a bit daunting, even overwhelming. Luckily, aspiring game makers should be able to find tutorials on the web. However if you're like me, you'll probably learn more about it just by playing around with the settings.
If you really want, you can go as far as making a long, Final Fantasy styled role playing game. This is where
you need to know a lot about programming. Typing out long commands and programming everything can be really difficult and time consuming. However if you're too lazy, or you can't be bothered to learn the coding, you can (fairly easily) put together a fun and cool adventure game, like the original Zelda game from the NES days. The themes are pretty much endless, ranging from space cowboy to regular cowboy.
The limits are mostly only limited to your imagination, and you'll find that just planning out a big game idea can be a lot of fun. If you need a bit of inspiration to get you creating, MZX also comes with a sampler game, called Caverns Of Zeux. It's fairly simple and straightforward but it gives you an idea of how the game engine functions. Again, if you're lazy, you can also edit the sample and make something different. If you've got the time, this is a cool thing to check out. Not only that, but you learn a fair bit about basic game development.
Also, for people not quite so interested in producing your own game, it comes with a couple standards.