During my undergraduate studies, I created a few small web games with friends, during Hackathons or as class projects. These were built with primarily with Javascript technologies (Node.js, Express.js, jQuery, Socket.io) and HTML5 canvas.
Surival of the Fittest was my favourite. It's a multiplayer "battle" version of Conway's Game of Life.
Then there was our agar.io clone, also known as Yet Another Agar Clone (YAAC).
This isn't exactly a game, but it isn't not a game either. Essentially, myself and some fellow software engineering students created a fake cryptocurrency as a prank on our school, McMaster University. It's actually a tradition for students graduating from engineering programs in Canada to pull pranks on their campus in their final year.
You can read more about it in my friend's Medium article!