Spore.

Don't get me wrong, it's nothing short of an amazing game. The problem was that I wasn't part of the hype back then, but I realized that it was disappointing for few. After playing Galactic Adventures, I really think Spore needs to be brought back. As a sequel. Even if Maxis isn't around here any more.

Spore 2 could have these features
-Underwater level
-A stage between tribe and civilization
-A voice slider and general voice options (in Spore, your creature most often sounds like a friendly male character, which isn't so great if you're using, say, a Peach creature). Just... more voices in general. Give creatures a choice of what voice to use, whenever it's a bird chirping or a lady in a singsong voice or a gruff, menacing man.
-Maybe more complex evolutionary paths
-Drive vehicles
-Better combat. Maybe make it even like Darkspore. But this whole "click a button and watch enemy take damage" is hardly "gameplay". Even the ranged stuff, they just home on your opponents and even pass through walls. Befriending creatures is even more shallow. If a creature has one part, level 3 sing, your other social parts don't even matter. In the space stage, it's also pretty much the same thing, with auto-aim and that stuff.

My biggest want are, however, is an even more fleshed Adventure Editor. Spore Galactic Adventures makes Spore so much better. You can couple it with better combat and a much bigger variety of Captain tools. There is an option for even more complex creature interactions, there are more "acts" to choose from, more ways for dialogue, maybe even multiplayer so you and another player can cooperate in the Adventure. Maybe have one player even build the Adventure while the other plays in it and vice versa. Have pick-ups you can actually equip, such as weapons you can use to slash or shoot.

In the end, yeah, we're going to get No Man's Sky, which sounds similar to Spore's Space Stage, but it doesn't have the same charm as creating your precious things and then see them flee from your space ship that resembles a giant Mario.