Little or no code engines
These are game engines that require very little (or minimal) starting knowledge about software development to begin with.
This is a markup language used for making branching narrative games.
A little online tool for creating text adventures!
An online tool for making adventure games where you navigate rooms!
An in browser engine for creating tile based block puzzle games.
This is a JS library based off p5.js and contains most of the gubbins needed for creating games of all sorts.
Larger more complex engines of interest
Unity is included here mostly because I have had prior experience using it and despite everything it is not all bad. This is quite a heavy weight program that allows for creating 2d and 3d games.
The Godoot engine is an open source games engine that is capable of creating 2d and 3d games.
This is an tool for making games for the Gameboy. It can also export to web.
This is an updated version of the gameboy development kit that brings it more up to date.
SDL2 is a media library for C that can "easily" be used to create games.