I might not be the best person to give advice about making the game Steam-release ready, especially if it's meant to be commercially viable. I'm more of a hobbyist dev, and I'm more leaning towards the kind of small games one would see on portals like Kongregate or Newgrounds or the game jams, rarely playing more complete releases.
I'm not much of an audience for larger idle/clicker games - it's fine when they're relatively short, but for longer games I'd rather pick some other genre. That said, I think when expanded upon, those kinds of games would benefit from self-expression - not just raw upgrades, but also decorations to place around, outfits and accessories to give to the beaver and the like. A while back I made an idle/clicker jam entry with various resources; elements were placed on a grid and some upgraded nearby elements instead of producing resources on their own, allowing for some optimisations people could figure out.
For the steam release, I recommend finding someone who would be genuinely interested in this kind of game being expanded upon (not just enjoying the jam version as-is the way I do) and asking them what they like in games like these. Maybe even getting several such people, to get more ideas to work with (but also make sure not to overscope or have some ideas clash with the design of others). Good luck! ^^












