first note that minetest is just an engine, not a full game.
the preinstalled minetest_game is minimalistic and only contains basic elements.
you can either add mods to the game or use a subgame (a preset of mods designed for working together)
depending on how much you know about games, you can make your own choices of mods, and maybe make some changes to the code to create the game environment that you like or just choose a subgame with a theme that you like most.
most of the subgames are still in development, so the good choices are few.
"carbone" is currently the most stable and balanced game and has everything that is in Minecraft and some extras.
all content is fully functional and you don't need to add anything else.if you want to create your own game by combining mods, i would recommend the mods made by TenPlus1.
(Ethereal mapgen, mobs, farming, teleporters, ambient sounds, ect.)
they are all compatible with each other and well designed.
most important if you want to use mods, is to know what you have and what you need.
when you install mobs, you also need armor.
the armor mod requires "inventory+" to provide apropiate formspecs and menus to equip armor.
inventory+ also supports a craftguide (must use) and bags to be able to carry more items and keep them safe.
the link to the carbone subgame is here:
viewtopic.php?f=15&t=12824it is the easiest thing to do.
if prefer to compose your own game and want to use the mods i suggested look here:
viewtopic.php?f=15&t=12824the last thing to know are the different mapgens:
v6 has only 2 biomes: forests and deserts.
you can also find jungles there, but that's it.
v5 and v7 have green lands, dry lands, snow lands, deserts and glaciers as well as 4 different trees.
v7 is the most stable of the three.
custom mapgens like Ethereal or the one used in carbone require mapgen v5 or 7 to work.
(v7 is probably the better choice as v5 tends to generate crazy landmasses that are more difficult to conquer.)
lastly, the "how to install":
mods are placed in the "mods" folder and subgames go into the "subgames" folder.
you will find these in your local ".minetest" folder. (in linux it is a hidden folder in your home directory)
sometimes the downloaded mods/games have "-master" in their name. if they do you have to rename them and remove the "-master", then everything should work fine.
PS: almost forgot: if you want to use mods, you must enable them ingame by selecting your world file and pressing the "configure" button. there you can turn mods on or off. this can also be used to disable unwanted mods from subgames.
in carbone this would be "meze" as this mod adds deadly instant kill blocks, you probably want to exclude those from your game.