chore: update README.md

The README is now somewhat full-fledged, with a short description,
screenshots, and download information.

Author: danielzting

README.md

@@ -1,2 +1,13 @@
 # Human Computer Simulator
-*Gamifying computer science education*
+*Human Computer Simulator* is a game where you get to become your
+favorite algorithm and or data structure.
+
+# Screenshots
+![Level Select](assets/levels.png)
+
+# Download
+This software is in an alpha stage of development and I do not plan on
+releasing ready-to-run builds until a stable v1.0 release. However, it
+is very easy to run it yourself. Just grab the free and open source
+[Godot game engine](https://godotengine.org), import the `project.godot`
+file, and hit the play button.