If you've been wondering what I've been up to, this is it: getting Steam Marines 2 ready for Steam Early Access.
To go over the more likely questions:
1) If you purchase on Itch you will receive a Steam key.
2) Itch and Steam will both receive the same game updates.
3) Steam Marines 2 has not had a discount to date, and it's not likely to get one anytime soon.
4) It will continue to be for Windows, Mac, and Linux. No plans for any other platforms at this time.
I am told that Steam wishlisting is valuable to gain visibility via the Steam algorithm so if you do wish to support me please wishlist it over there!
If you have any questions please feel free to ask them below!