2D Graphics Engine

Overview
Hello, so I'm slowly progressing with my OpenTK, OpenGL and whole C# adventure. I'm taking opportunity to start development diary so here I am :) I have started writing a small engine with OpenTK, that handles ONLY 2D rendering, but completely removes need to use any OpenGL function, while cooperating with other parts of OpenTK. I haven't decided for the name yet but that's not important I think.

The goal is to build a small, easy to use engine capable of building small 2D games together with OpenTK.

Engine doesn't use any scene-graph, you must draw each image every frame manually. I think this way it's cleaner and faster when working with 2D graphics. However, Gui uses a GuiManager which will draw all widgets at once.
To use engine, engine code is linked directly with game code. If you don't need some parts of engine you just don't link them.

The colors are passed as unsigned bytes (0-255).
The positions and sizes are passed as integers, meaning the x and y position of pixel on screen, where 0,0 is in the top left part of the screen.

Features implemented:
- Images loading/drawing (rotating, scaling, blending, drawing part of image)
- Animations(Sprite) (frames rendered from one texture, same options as image)
- Particle systems (uses single VBO, Point sprites)
- Custom VBOs

Features planned:
- Basic Gui(first widgets done)
- Complete documentation/examples(some examples done)
- Shaders

Screenshots: