Navigate to the following directory;
When you've downloaded the game you need to unzip the contents to wherever you want to save it to. Then you have to enter the folder where you put it, Right-Click and go down to Properties and change it's permission value to execute. Or from Terminal you can just run;
chmod +x V1.04_Raft_LinuxUniversal
you will have two different binary files, you have LinuxUniversal.x86 and LinuxUniversal.x86_64, run it on whatever your system uses.
one you've done this just double click and the game will load.
At the moment I'm using Linux Mint, and it's been pretty fairly decent for gaming on since it's not using Unity as its core feature, but comes readily available in Cinnamon, KDE and Mate. You could go for super light and fast alternative like Arch Linux where you get to build and choose what stuff you want installed on your system, install your own preferred desktop manager. I might recommend Wayland instead of X11 for the display server, but it's still in early build development, and you may have issues using official graphic drivers like Nvidia's, since it's built around open-source drivers, but I do believe there is workaround support for it. Running a minimal setup would be the way to go.
Sorry to burst your bubble, but Ubuntu isn't really the best. I use to to use it alot before I tried other distros that suited me more, some of the ones I've used have better performance and lesser memory usage than what Ubuntu has.
If your computer has a dedicated video card inside then the drivers for that should be working alright, or if you only have Intel HD Graphics and it's running off that instead. If you have both then you might want to check about running both at the same time. The game could use some optimizations in it's performance I'll give it that, framerate may drop every now and then but it seems pretty stable in its current development.
It would be disappointing to see development of this game on Linux to suddenly drop just for a few issues that can be worked on and fixed.
also this isn't much but I've made a little debug dump of running the game through GDB Debugger, here's a link to it on Pastebin to show what's going on; http://pastebin.com/UCxpfJ9F
A few minor SIGSEV and other stuff in there. Finer details can be seen at the bottom which should be worth figuring out.
Firstly, I think it runs really well on Linux.
Secondly, I think you need a better computer and have the right drivers installed on Linux if you're having performance issues.
Thirdly, the devs have already acknowledged the cursor issue and are currently looking into why that is happening.
What you got is the Linux binary executable, so you need to right click on the binary executable and go Properties and click on Permissions tab and set to executable. Should see something like this; http://i.imgur.com/iVQpZjK.png
I don't get why it doesn't ask you if you wish to set it to executable when you click on it so you can run the game like this http://i.imgur.com/FyqqgbF.png
Most Linux distros have the option of making a binary set as executable when you click on it, strange how it doesn't ask you that instead of trying to open with another app which isn't the normal behaviour of running a Linux application. but like others have stated right clicking on the game and going to Properties you can change it to executable from the Permissions tab, or by command line by doing
chmod +x on the binary executable.
That link you have provided is not the answer. He has the Binary executable for Linux which run on Mono Runtime, what you've linked to instead is running Windows (EXE) files on Linux in Wine.
I've got a strange occurrence that happens with the game on Linux where if I've been playing for a while, guessing 2-3 hours playing the game randomly locks up but the in-game cursor can still be moved around, trying to close the game by clicking on the window close button or from the app tray doesn't seem to respond to being closed at all like normal, and I end up having to terminate it by the process manager. This has happened at least twice now already where it randomly locks up. I can try see if I can grab a crash dump but it could take forever to wait for it to randomly lock up after a while.
From what I've been experiencing from this game so far, here are just some suggestions I think would better the game.
well those are just the few things that come to mind for me anyway. Oh final thing is don't make the shark pass through the raft or attack raft parts that have support beams and walls on them.