Enter the Gungeon - Robot Gameplay
So here is some gameplay for the robot. As you might've guessed, the robot offers the most combat potential, but is also far more difficult than any of the starting characters.
The idea behind the robot is simple. Your main gun has a lot of bullets, which also do electric damage, that you can chain with your active skill to wreck enemies.
There isn't much more to this little guy, besides the fact that he can't gain health and is limited to armor, but offers a nice change of pace. Especially if you can get a really OP weapon on the first two floors to give you a huge boost in power.