ECoS is described as 'modern fantasy console based around the solid foundation of an Entity-Component-System architecture (ECS)' and is a Game Development Tool in the Development category. There are more than 10 alternatives to ECoS for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Self-Hosted solutions. The best alternative is TIC-80, which is both free and Open Source. Other great apps like ECoS are PICO-8 (Paid), Voxatron (Paid), Bitsy (Free) and quadplay (Free, Open Source).
VectorBoy is a fantasy console that can be used to play your own games written in the LUA scripting language. Unlike other systems of its kind, it doesn't use pixels to display graphics. Instead, the screen displays straight lines to form graphics of all kinds.
LowRes NX is a simulated retro game console which can be programmed in the classic BASIC language. Make your own retro games on a virtual game console. Create sprites, tile maps, sound and music with the included tools.
WASM-4 is a low-level fantasy game console for building small games with WebAssembly. Game cartridges (ROMs) are small, self-contained .wasm files that can be built with any programming language that compiles to WebAssembly.
BASIC8 is an integrated Fantasy Computer. Create, share and play disks in a modern BASIC dialect. Use built-in tools like sprite, tile and map editor to develop games fast while having fun with retro aesthetics.
CHROMA-60 is a Fantasy Computer programmed in assembly language for an emulated 8-bit CPU and has a scanline based renderer that supports raster effects and allows for very colorful images despite the 1-bit display.
PQ93 is a fantasy console for making small games. It is available to download and run natively, but you can play the demo in-browser above. Included in PQ93 is a command shell and editors for code, sprites, sound effects, music patterns, and maps.