This game definitely has one of my favorite UI so far. Very clean and well structured visually. Also having options on the pause menu is a quick way to win me over.

I guess one of my main criticisms is related to selecting the individual stars. I figure the clickable region is small since the stars can spawn fairly close to each other, but it does provide a hindrance since you have to be more meticulous with your clicks. I might have missed something in the instructions related to this but right now that's my biggest gripe.

If you plan to continue working on this post-jam, it might be a good idea to include additional visual cues on what elements each star is producing (like making a star blue for oxygen or a mixed color for stars producing two elements at once).

I also ran into a crash around 10 minutes in when i combined Oxygen with Oxygen on a star. Not sure if it was related to that but I included the error regardless.

___________________________________________
############################################################################################
FATAL ERROR in
action number 1
of  Step Event0
for object obj_stars:

DoAdd :2: undefined value
at gml_Object_obj_stars_Step_0
############################################################################################
--------------------------------------------------------------------------------------------
stack frame is
gml_Object_obj_stars_Step_0 (line -1)

Good luck on the rest of the jam!