Sadly, not all games in the the Humble Hooked on Multiplayer 2018 Bundle are on Linux but there's still some goodies!
For pay what you want, you can grab Tumblestone. The description of this one on Steam made me curious, it claims you can generate up to five Steam keys yourself for it per day to give to your friends. Don't think I've ever seen another game do that before.
If you decide to spend some more to beat the average, you can get Besiege and Hover. I have to admit, I've wanted to take a look at Hover for a while, so I might pick the bundle up to take a proper look.
Fancy grabbing Rocket League? It's the top game in the bundle if you spend $14 (about £10.30) or more, which also comes with $2 Humble Wallet credit for Monthly subscribers. You all know my thoughts on Rocket League by now, it's absolutely brilliant and this price is well worth it.
There's other titles too, but as I said not all are on Linux. Find the Humble Hooked on Multiplayer 2018 Bundle here.