SteamDeck Install

Credit: /u/asmithatx via Reddit
https://old.reddit.com/r/BattleTechMods/comments/11rzdp7/install_rougetech_and_bta_3062_on_steamdeck/
!! WARNING !! : Running RogueTech natively on SteamDeck is not supported at the moment. 
Demonstration at: https://youtu.be/xFvTCX4l8HY
Install RougeTech (and BTA 3062) on SteamDeck
(starting from factory default) Recommend using a keyboard + mouse + external display.
# Connect the Steam Deck to wifi so that it'll have Internet access.
# Press the Steam menu button -> click "Power" -> "Switch to Desktop”.
# (if necessary) Purchase BATTLETECH and all DLC but do not yet download.
# Go into BATTLETECH's "Properties" -> "Compatibility" and choose "Steam Linux Runtime" - now you can download the game (it will pull the Linux native version of the game rather than the version compiled for Windows).
# (preferred) Turn off the Steam Deck display and run off external display only and use a keyboard and mouse for all remaining steps.
# Right-click Steam icon in the lower right corner, choose "Library", click BATTLETECH, launch the game one time and exit once the main screen successfully loads. Once the game exits, click the gear icon on the right and choose "Manage" -> "Browse local files”.
# In the file browser window that pops up, click the hamburger menu in the upper right and choose "Show hidden files”.
# Navigate 1 directory higher to be in the "common" directory. Create a folder called “RougetechLauncher".
# Launch Firefox (you may have to install it) and download the Rougetech launcher (https://discourse.modsinexile.com/t/rogue-tech/134), saving it to the "RougetechLauncher" folder you created in "common".  Make sure the file size matches what the website says it should be (~42 MiB)...sometimes I get a bad download, will be smaller than it should be.
# In a file manager window navigate to the "RougetechLauncher" folder, right click somewhere in the open space of the file manager window and choose the "Open Terminal here" option. Once the terminal has launched, right click its icon in the task bar and choose the "Pin to Task Manager" option for faster access in the future. 
# Next we'll need to add a password to the "deck" user we're running as in order to issue commands with administrative privileges. In the terminal window type "passwd" (with no quotes) and hit enter, you'll be prompted to create a password - follow the prompts.
# Run the following: sudo steamos-readonly disable so we can make changes to the normally read-only Steam operating system.
# Issue the following commands--to initialize the the pacman package manager's keyring:sudo pacman-key –init--to populate the keyring with the latest:sudo pacman -S archlinux-keyring-- to update the package manager's local cachesudo pacman -SyIf all that went well you should now be able to install the "winetricks" package with: sudo pacman -S winetricks 
# In our command terminal we should still be in the  /home/deck/.local/share/Steam/steamapps/common/RougetechLauncher folder (if not then "cd" to that location), issue the following command: winetricks and click "install", "yes" or "ok" to any prompts offering to install missing packages such as “wine-mono"
# Once winetricks loads, click "Ok" on the default selected option (which is "Select the default wineprefix") - if prompted to allow statistics to be collected answer yes or no (your choice). Next select "Run winecfg" and click "Ok". - On the initial "Applications" tab you land on, change the "Windows Version" dropdown at the bottom from "Windows 7" to "Windows 10". Do not click on the "OK" button yet.-Next click on the "Drives" tab and check the box at the bottom labeled "Show dot files" as this will let us see hidden linux folders in the WINE environment,-Finally, click "OK" to save these wine preference changes.-Click the "Cancel" button twice to close the winetricks application (the changes you made to your wine preferences will still be saved)
# Issue the following 2 commands: mkdir ~/.local/share/Steam/steamapps/common/BATTLETECH/Mods; wine RougeLauncher.exe 
# Then get into the folder the BATTLETECH folder and run one more to make an alias for the executable:cd ../BATTLETECH; ln -s  Battletech Battletech.exe
# Now that we have the launcher running we need to point the "Install Target" and "Checkout workspace" fields to their appropriate spots: -Click "Ok" to dismiss any warnings about memory (we will address that later).-Click "Advanced Mode" and then click the "Browse" button for the "Install Target". The linux file system will be mounted as the "Z" drive so begin by single-clicking on "My Computer" and then double-clicking on the "Z:" drive. -Navigate the following: Z: drive -> home -> deck -> .local -> share -> Steam -> common -> BATTLETECH -> Mods-For the "Checkout workspace": If you haven't already previously downloaded and saved the installer files, first create a folder to store them: mkdir ~/.local/share/Steam/steamapps/common/BATTLETECH/Mods 
# Then navigate the following in the file explorer and then click "Open":-Z: drive -> home -> deck -> .local -> share -> Steam -> common -> BATTLETECH -> RtlCache
If you have previously saved these installer files to a USB drive, it can be accessed in "My Computer" on one of the other drive letters as long as it was connected prior to launching the RougeLancher.exe - just navigate to the RtlCache folder on your drive and click "Open" in the file explorer window.
Notes/Warnings:
If you cannot see the ".local" folder in /home/deck then you likely need to see step #15-you should just copy the whole RtlCache folder from your USB drive to  /home/deck/.local/share/Steam/steamapps/common/BATTLETECH/RtlCache as the whole rest of the installation runs much faster, in fact the installer can time out pretty easily if the USB bus speed isn't super fast. Save yourself the headache and do this.
Finishing the whole thing out:
Click the "Set Preferences" button and then "Browse", navigate to: Z: drive -> home -> deck -> .local -> share -> Steam -> common -> BATTLETECH -> Battetech.exe Click the "x" in the upper right corner of the "User Preferences" windows when done.
Click the "Update/Install RT" once all the above has been completed. Once it prompts with "No data could be found at the current target location, New Install to be done" click "Ok" twice. Choose any options you want but be sure to choose "Original Fire Fx" and un-check the "RougeTech Perf Fixes" (both of which are necessary in the Linux environment)
Click "Ok" and then "Yes" to proceed with the mod install
While its downloading and installing, back over in a terminal window issue the following commands to increase the pagefile size from the default (1G) to 10G:
sudo swapoff -a
sudo dd if=/dev/zero of=/home/swapfile bs=1G count=10
sudo mkswap /home/swapfile
sudo swapon /home/swapfile
Also, increase max number of open files the OS will allow (nofile or DEFAULTLimitNOFILE) to at least 32768 in the following 3 places:
/etc/security/limits.conf/
etc/systemd/user.conf
/etc/systemd/system.conf
You'll get an "Update Complete!" window once the mod is finished installing, click "Ok" and close the RougeLauncher application, Reboot when the open file limit changes have been saved, the swap file changes are complete and the mod is done installing
Back over in the command line terminal, make sure you're still in the /home/deck/.local/share/Steam/steamapps/common/BATTLETECH folder and issue the following command: chmod a+x run.sh 
Then in the Steam application, click on the gear icon for the BATTLETECH game, choose "Properties" and input the following for "LAUNCH OPTIONS":/bin/sh -c ./run.sh %command% 
Finally, launch BATTLETECH from within the Steam app (not from the RougeLauncher). After confirming that ModTek loads and you see the "RougeTech" logo on the main loading screen, quit the game and restart the Steam Deck.
Now when launching BATTLETECH from the main Steam Deck interface (not the Desktop) you'll be launching RougeTech!