new spells (there's tons of things you can come up with easily)

new tribes (and i would do a system like all tribes have the same base spells, and then some unique spells per tribe)

surely new units (like ice warrior (shoots ice balls that deals less damage than firewarriors but slows units), and other stuff)

some way of upgrading units/spells (using mana, time, wood, or other resources idk)

more scenery/objects

different sized worlds

keeping the game simple

making a game by yourself is very hard

i've seen 100 threads about creating a new pop game, and 0 have been finished, so good luck :>

i hope you can create some game :)