Make the game area larger. Once you get to the pop limit and can't build anymore huts it tends to be a whats the point of doing anymore type of thing. Maybe more techs or the techs you have cost a lot more so it takes a little long to get to that finishing goal.

Have the exploring actually have a char go into the jungle and explore maybe come back after so long with a collectible or food or something.

sorry if all was mentioned before I've been reading a lot of it but know i've missed a lot too

of course continuing to add to the game like this will turn it into a big game like Age of Empires (the first was always the best)