Since a Linux release isn't in the near future I took it upon myself to try everything within my knowledge to get Tower Unite to launch and play. Let me save you the read and say that I have had no luck, however, let me share what I found in case someone has input. There are two paths I took each gave different results...
Alright, so what I did was created a Virtual Drive for steam using Playonlinux. That doesn't work on its own since the by default Steam is ran in 32-bit. This will not work since Tower Unite is a 64-bit game hence Steam won't even let you attempt to download it. What you need to do is download the exe from their website and do a manual install. I used the following for my settings:
Wine Version - 3.7 64-bit
(Please Note the runtimes are likely to be pointless however I grabbed them all for other games I planned on installing at a later date. Install them if you wish this is just what is installed, you may get varying results.)
Okay after you finish the installation you can begin downloading Tower Unite. If you get errors up to this point you should check steam's Winehq profile to see if other ran into your issue. My issue comes after you download Tower Unite. You try to run it and get a shader cache error telling me to run the game UNCOOKED. This is a good laugh to have at 4am all the work to learn you games are cooked on a stove or in the deep fryer. Jokes aside this is solved by running the game uncooked setting the launch perms with -game . This will launch the game but no window will pop up no prompts what so ever. My thoughts are this has something to do with the engine and how it debugs things. I haven't fiddled with Unreal Engine before so that's just a theory.
This is a relatively short ran the VM with Windows 7 plus guest additions. Also with Virtual Box's 3d and 2d acceleration. Downloaded steam, downloaded Tower Unite, and launched it to be greeted with the message stating I need Directx 11 level 10 to play. This is likely a limitation with Virtual Box not being able to handle DirectX 11. I am pretty sure my 1070ti can use DX11 sooooo rip.
Welp it is late so I'll leave the Linux Community of Tower Unite as well the devs of TU with this. Sorry in advance for the piss poor formatting.