We used ecsy.js to create a prototype of a web game engine with only React, pixi.js and ecsy and I wanted to show it to you.
We first did it without ecsy and we had problem with performance (garbage collector slowing too much the framerate). With ecsy everything is fine :).
You can test it here : http://steamdungeon.com/
Or check a basic video of the gameplay here : https://www.youtube.com/watch?v=-LywmsCr_7s
PS : I wrote an article (french only currently sorry) that explain basically functionnalities developped (multiplayer, random level generator, …) : http://kieirra.surge.sh/2020-07-05-steamdungeon/)