Here are some of my notes about the three winning applications (in alphabetic order)
PogoStick with Coins. Doesn't work on low-end systems. Hard controls. The game is nice, but not really playable due to my inability of controlling the stick. The scene is only basic, but has nice post-processing(?). I didn't notice bullet except in the code. Looks like there's music, but I have either shader support or music
The code does not show any OOP besides the necessary things for custom nodes. Instead many globals...
Flocking Boids. Really cool stuff with swarms (motion of...), though the strategies fo the swarm are not predictable. The scene is nicely laid out with an overwhelming choice of additional elements. The teleporter animates really cool and is pretty usable. The code is clean and straight forward.
The Island. Full casual game with all necessary stuff. Moving meshes (trains), particles, very good camera, some kind of physics support for the island tilt.
The game uses a very nice scene and very simple, though addictive gameplay. It's a little too hard in the basic setup, but should be very good playable after some minor balancing.
The code is really small, clean, and very promising.