Intrusion 2 [official site] is one of the best games. It’s a 2D side-scrolling shooter with physics-driven animation and a commitment to expansively silly action. So, for example, one of its bosses is a helicopter with arms. It punches at you then pumps its fist when it wins. When you destroy its helicopter blades, it uses its arms to drag itself towards you along the ground. And when you destroy the rest of it, you go sliding down a mountain by using its remains as a snowboard. Then you get given a mech suit with a sword and shotgun.
Now its designer is making a new game called Jetpack Squad [official site] and the GIFs of its in-development form are enough to suggest it’s even more physicsy, expansive and silly. There are six of those GIFs below.