As mentioned elsewhere, we've locked off additional sales of the game on all platforms until launch.
If you previously purchased the game on itch.io, you're eligible to claim a Steam key.
To claim your key:
- Log in to itch.io's website ( https://itch.io/ ) using the same account that you used to purchase AvenColony.
- Click on the account drop-down in the upper-right and click "My Purchases"
- Select Aven Colony
- Hit the Downloads button
- On the Download page, press "Get Steam key"
- The following image shows a reference for that: http://avencolony.com/wp-content/uploads/wpforo/default_attachments/1491406477-claiming2.png
This support page on itch.io may also help: https://itch.io/docs/buying/already-bought
Once you've installed the game on Steam, you can find instructions here for copying over your saved game files.