Besiege

In Besiege, you build impossible siege weapons and launch them to see if they will work. The game uses realistic physics system and was often compared to Kerbal Space Program. Each machine has to be assembled before use. The player is given a variety of modules to build from, and they include all kinds of weaponry, not necessarily medieval. Using improbable combinations of wheels, drills, spikes, blades, propellers, cannons, and water hoses you can turn your death machine into a plane, a tank, a robot, or rather something not found in the real world. Each machine is built with a purpose to complete a level objective, be it to destroy an enemy castle, slaughter the opposing army, or move an object to a destination. Levels include many kinds of obstacles, such as landmines, trees, rocks, and enemy soldiers.
The machines can be of any shape, however grotesque or impractical. If they’re not well-thought or too shaky to withstand attacks and obstacles, they will fall apart, catch fire, or explode. However, failing spectacularly is half the fun of Besiege.