Is it difficult to build a server to host a videogame off of?

Is it difficult and require really top notch equpment to run a server that host a game? Is it legal to host a game out of your house?

What is a server after all? It's a PC. There's no magic to it. Most multiplayer game servers are primarily bottlenecked by their upstream internet connection speed. The server typically needs to load maps, and it needs enough ram to hold these maps and the player connection info into memory. Depending on the game, anything slower than a T1 is not going to offer much of a game experience. If you just want to host a game for a few friends then you might be able to get by with a lot less. Most multiplayer games have some information about hosting servers that will indicate the amount of bandwidth needed per player. This will tell you how much upstream bandwidth you need.

An finally, there is no reason you can't host a game server. It's your bandwidth that you pay for.

it is not leagal to host game on server, until u get a license to publish. But u can definitely host games that u develoed.