Hello everyone!
Until the peer-2-peer online multiplayer mode releases in our summer update, the current method to play online is via Steam's Remote Play function.
Here are some notes that will fix some common problems we see and get you climbing the mountain with your friend!
1. After starting the game with Remote Play, press Shift+Tab to open the Steam interface. There you'll be able to see a list of your friends to invite.
2. To avoid running into issues where one play cannot use the keyboard to play, make sure you allow them access by clicking the right option by their name.
When using Remote Play, there can be a delay or a performance loss depending on the distance between you and your chosen partner. Closer distances will perform better.
Thanks everyone for your support so far. Have fun!