Using a Steam Deck? You can install Additive on there! This may also work similarly on other handhelds, but I haven’t tested. First we’ll install Prism Launcher, and then install the modpack.

1. While the deck is turned on and is in Gaming Mode, hold down the power button and select “Switch to Desktop”.
2. In the bottom panel, look for the 👜 “Discover” app.
3. Press the search bar in Discover, and then press X to open the keyboard.
4. Search for “Prism Launcher”, and then tap install.
5. Launch it. When it asks you for the amount of RAM, set the maximum to 4096 MB. Connect your account, and once it’s complete, close the launcher.
6. Tap the Steam Deck icon in the bottom panel, and then look for “Prism Launcher”. After that, right click Prism, and “Add to Steam”.
7. Now, go back to Gaming Mode by double tapping the file on the desktop or opening Steam and switching back.

Prism is now installed. Now, we can install the pack.

1. Launch Prism from Gaming Mode.
2. Tap “Add Instance” in the top left of Prism.
3. Select the Modrinth tab.
4. Press STEAM + X together to open the keyboard. Then, search for “Additive”.
5. Tap on Additive, select your preferred modpack version, and then install.
6. Go into the instance’s mods tab and install Controlify. Optionally, you may also want to install Resourcify.
7. For the first launch, you will get a notice at the start of the game to download some libraries and calibrate your controller. Simply follow the on-screen instructions and you shouldn’t have to do this again.
8. After launching, go to your video settings and enable fullscreen to fix the aspect ratio. Enjoy!