Step 1: Go to your Gish in your Steam Library and right click it, go to Properties.
Step 2: Go to Betas, then select the drop down box and select version170 - version 170

How do you make sure you can actually unlock Achievements now? By unlocking one!
Here is a quick easy Achievement that is great for testing since you can unlock it in the menu.

Real Friends
Played a four player game


Step 1: Start up the game and go to versus
Step 2: Pick Sumo OR Football (either works)
Step 3: Pick any level that supports 4 players
The moment the game starts, the Achievement should pop instantly

If you already fulfilled Achievement requirements before on the most up to date version of the game I'm sorry to say that the progress does NOT transfer, you'll have to redo it.

Please leave a thumbs up rating if I helped you out... Also, I know it feels a little trashy to ask since its a very simple guide but I would also appreciate any awards too. :)

I am probably gonna make an in-depth Achievement guide for Gish later, but this is all for now, thanks for reading.