Yes free assets were used for the graphics. While I made some changes to them to fit (For example the obelisk breaking animation was made from scratch using the obelisk sprite as base) and made some small sprites (the portal sprite and some other), my art skills are nowhere near the level necessary to make the whole graphics in this amount of time. Music and sound effects are sadly missing, I wanted to add if I had some time left, but I ran out of time.
There certainly are many things to work on. I want to remake most of the systems as the code structure is awful and change many other things. But thank you for playing :)