Awesome! I had been working on a similar project couldn't figure out the snow on the trees for the life of me! It's great to see how you approached it. The work look great! Thanks for sharing your process.
I believe author would be surprised that it's not american, but soviet bunker :)
Helper classes for animations, tilemaps, text, backdrops, and more with z-sorted render lists for easy depth management.
Fast and manageable rectangle, pixel, and grid collision system with a plethora of built-in collision options.
Powerful motion tweening for linear, curved, and path-based movement as well as spritesheet support and image transformation.
Sound effect support with volume, panning, and fading/crossfading, complete with one-line sound playback.
Quick and efficient particle effects and emitters allow for beautiful particle systems without slowing things down.
Framerate-independent and fixed-framerate timestep support allow you to decide what mode is best for you and your game.
Simple keyboard and mouse input state checking makes setting keys and events incredibly easy, yet powerful.
Handy console for real-time debugging and information tracking. It even allows moving the camera and inspecting entities while playing!