This is a free and open source game engine and toolkit, that allows to create games of platform genre. The basic idea of this project is to make it possible for every user to create platformers with existing or self-drawn sprites. The first work on project began since December 2013, and the project was founded in a March of 2014. The project is formerly known as PGE Project (a.k.a. Platform Game Engine Project).

TheXTech is a free and open-source game engine for Mario-like platforming games. There is a complete and extended source code port of the Super Mario Bros. X 1.3 game engine (later just "SMBX"), and its direct unofficial continuation after development halted in the 2011th year. This engine preserves full compatibility with levels and episodes made for the original SMBX game, including its repacks. And it's allowed to create brand-new Levels, Episodes, and content packs. Unlike the original SMBX game that depends on Windows and x86, TheXTech can work on many operating systems (including Linux distros, macOS, xBSD, Android, Haiku, etc.) and processor architectures (including x86_64, ARM, PowerPC, MIPS, etc.).

Free and open source role playing game interpreter and editor compatible with RPG Maker 2000 and 2003

A free and open-source 2D game engine.

Pulp is a click-and-place, fun, quirky game studio for Playdate. Make a game with no code, or maybe a little code.

A free, open source, project oriented level editor made for indie game developers by indie game developers.

a tool for drawing and assembling graphical hypertext games

GB BASIC is a retro Fantasy Console that generates ROMs compatible with the popular handheld game console.

A quick and easy to use drag and drop retro game creator for your favourite handheld video game system.

Downpour is the best app for making games on your phone. Collage together photos, drawings and text, and then connect them into an interactive story. It's genuinely quick and easy to use — you can make a game before your tea has gone cold. Once you've made a game with Downpour, what then? You can share it with your friends inside the app, or post the link for anyone to play.

bipsi is a tool for making small games where a character explores a world and interacts with its inhabitants.