Can I remake a game I don't own any copyright to?
There's a online browser game which I played 5 years ago. Some time ago, this game was shutdown because its developer went bankrupt. I want to re-make this game and provide it to Web again. Can I do this? Or there's some copyright problem or something like this?
Somebody still owns the copyright, trademarks, et cetera for that game and related assets, even if the game is "shut down."
In order to use any of those, you would need permission from the holder of those rights.
You can make a game that is mechanically similar, as game mechanics themselves are not subject to copyright. But you cannot make use of anything that is subject to copyright, trademark, et cetera.
It depends on the game and the nature of the remake.
Game mechanics cannot be protected by copyright, trademark, or patent. You can freely copy the mechanics of any game you want, as the basis of a new game. (This is why there are so many clones of things like Scrabble and Tetris out there, Snake clones are a common programming exercise, and many computer RPGs have mechanics that are strongly reminiscent of those from Dungeons & Dragons.)
However, the creative aspects of the game are protected by copyright. You'll need entirely new artwork, created in a way that doesn't make it a derivative work of the original (eg. by giving the artist bare-bones descriptions of what you need). Any re-use of the original storyline is entirely out: I can't picture a way of using it as the basis for your new game that doesn't create a derivative work.
Additionally, the game's name is almost certainly protected by trademark, either registered or common-law.
