Minetest is a game which is in the style of Infiniminer or Minecraft. It is a sandbox game, you can explore the vast land (limited to +-31000 blocks), mine, craft and make fortresses if you want. It is also free/open source software and can be downloaded for free as well.
There are two versions at this time, the stable 0.3 version and the current-in-development 0.4 version. There are some differences in the 0.3 and 0.4 versions, and in my opinion the 0.4 version is more fun to play. There are only two drawbacks in the 0.4 version, and that is:
- No enemies, but there are three in the stable 0.3 version.
- Apples (these give you life in minetest, but you do not hunger in minetest) are quite rare compared to 0.3.
However, there has been some major improvements if you compare the stable 0.3 version and the developmental 0.4 version. The improvements include:
- Sound is added
- Better graphics
- Easier to make and include mods
So, if you would like a more Minecraft-like experience with e.g. with redstone or ores, you can download some mods and (in Ubuntu 12.04, and Minetest 0.4) put them in the “/mods/minetest/” folder if it exists. Otherwise you would have to make the folders within your Minetest folder. I know that my friend, which I visited a few days ago was quite thrilled when he saw that the game had developed as much as it had from version 0.3 to 0.4. And he is a (what I would call a die-hard) Minecraft-gamer, so it is probably the best result you can get.
I have had quite fun with this game, and I hope you will enjoy it too.