I cannot overstate how fascinating this is as a feat of coding, optimization, etc. This game has over 70 unique enemies and fits in around 63 kilobytes. To put into comparison pokemon red takes up 1 megabyte (1,000kilobytes) and something like the pokemon diamond and pearl remakes takes up around 7gb (or 7,000,000kb). https://www.youtube.com/watch?v=-IIg-prpV4M