Bisiege is a game about building siege engines, and destroying things with them. It is a sandbox really like no other, and you're limited only by your imagination, and the game's robust physics engine to lay waste to foes.
You get a variety of materials and blocks, essentially, deadly lego to build your arsenal with. You're then presented with an objective, and you must do it. Through perseverance, natural selection (enhanced by your design) you will find success.
My only criticism is that ... sometimes, you spend such a long period of time making what appears to be an incredible siege engine, then you realise... for the task at hand, it is terrible. As a result, the game is not very forgiving of your time, and failings, and that's okay.
This game is essentially an "Incredible Machine" type game where you get given a whole set of objects, a space to combine them, and then a simple task to complete.
Only, most tasks don't end up being simple, and you often end up with flaming piles of wreckage. The game does not hold your hand apart from some brief tooltips, to get you started, then you're left alone to find success on your own.
This is totally fine.
The visual design of this game makes it feel like an excellently designed digital toybox, where there's no consequences. It's an outrageous, understated game in the way in which it goes about its business - and I highly recommend giving this game a good, hard go. It is oodles of fun.
The ruins of my siege engine, destroyed by a monolith.