Upgrade game?

I got the game from Steam, but I see now on your website you can get 3 different tiers,
Base for $24.99
Patron for $39.99
Loyalist for $74.99

was wondering if I can somehow pay the difference and get tier 3 or would I have to buy the game again?
If I buy the game again can i give the steam key to someone else and use the bonus stuff on my account or is that all tied to the new steam key?

Also can you take just donations?

I’m actually looking for this same information.

It you bought the game recently you should be able to return it on steam. I’ve never actually used that feature, but i know it’s possible now.

only if you played less than 2 hours and within like 48 of buying it(i think this last part might not be true).