Free sandbox games like minecraft?

I would like a game like minecraft thats more realistic, and has better graphic, 3d trees etc.

You can also play blood and sword or worm

Try torrent version of Terraria or Starbound, that games are 2D but really playable.
You don't need high spec computer for that game.

You can get free games here: http://www.points2shop.com/register?ref=ILovePandaz It's a site to get free stuff.

Cheers, Mike

How about city builders with sandbox mode? Is that something that makes sense for you? If yes, I'd advise you to check out Ancient Rome 2 http://toomkygames.com/games/ancient-rome-2
Megapolis http://toomkygames.com/games/megapolis
Townlopolis http://toomkygames.com/games/townopolis
Romopolis http://toomkygames.com/games/romopolis

There's a really good list available here with over 50 games: http://gameslikefinder.com/games-like-minecraft/

The best of the free one of all would be Terasology, the graphics blow Minecraft out of the water.

Some other options that are free:
Wurm Online
StarMade
Salem
LunaCraft
Kogama