This is the didactic proof of concept implementation of a bare minimum chess engine and GUI I've developed to help people learning the very gist of chess programming. This work is dedicated to hobby programmers who eventually want to come up with their own programs playing either standard chess or chess variants. Every chess variant presented here is available as a single stand-alone HTML file with heavily commented javascript source. It can run locally in the browser on computer or mobile device. Some nitty gritty rules are dropped for simplicity and clarity. The entire engine is the single function that takes board position as an input and outputs best move found within a fixed depth search. Every variant is a derivative of the standard chess with some modification to fit the rules of the specific variant. All the features and limitations regarding a particular chess variant are listed below.