Before I list the things I'd like to see or think would be cool to see, I'm just gonna say most have most likely have been listed by other people.
1: Doubling the marker block limit/clipboard save limit.
A larger marker block limit would really be nice for larger scale builds, or terraforming projects while a larger save limit would come in handy for people who build large things and like to save and move them from world to world.
2: Being able to make full blocks with posts, slabs, and corner blocks as well as the addition of sideways slabs.
I don't know if it is possible but it would be cool to be able to have a different interior wall without having two block thick walls, as well as the ability to make checkered or custom (kind of) blocks with posts and corner blocks.
3: The addition of some sort of biome system alongside the infinite worlds update.
Seeing mountain ranges, large grass plains, deserts etc would be a nice feature in the game making the worlds feel more lively, and maybe new blocks and wood types with different textures along side those?
4: Larger mob spawning groups as well as more animals.
The animals feel kind of small, things like boars, sheep, horses, the list goes on would help survival and dig deep players feel less lonely in their worlds.
5: Custom structures that generate in your game.
Like number 2, I don't know how complex it would be to add something like this, but things as simple as small houses or as grand as abandoned temples atop hills would be great to see in Total Miner.
6: The ability to make custom "skins" or unlockables.
I love how you needed to complete goals to gain new characters to play as in TM:F, and am hoping that comes back, but what I'd really like to see is a way to make my own player ingame to fit what I wanna play as.
7: CCTV Screen.
Maybe a block with the ability to link up with the CCTV script and display what you would be seeing if you were to run that script yourself, I don't know what is really possible and what can be done for sure, but this was one of the more unique things I thought of.
8: Better world customization options.
Changing how your world loads is very limited at the moment, maybe an option to change the Survival and Creative height limit to up to 1000? As well as choosing what and what not to load by default into the world, ie shaded grass blocks.
Those are all the things that really come to mind when I think of the main things I'd really like to see added into the game right now, I can't wait to see how the game progresses now that it's on Steam and coming to PS4, keep up the good work Craig!