RetroPie Tweaks/Setup for Raspberry Pi 3

Install RetroPie using the Raspberry Pi Imager:

1. Download the Raspberry Pi Imager and install it.
2. Launch the Imager → Choose OS → Emulation & Game OS → RetroPie → select the latest version for your Pi model.
3. Insert your SD card into the PC and choose it under Storage.
4. Click Write and wait for it to finish and verify.
5. Insert the SD card into your Raspberry Pi and boot — it starts straight into RetroPie.

Prefer a manual image? Grab it from the official RetroPie downloads page and write it with the Imager's Use custom option.

Load your games from a USB stick instead of the SD card:

1. Format a USB stick as FAT32.
2. Create an empty folder named retropie on the root of the stick.
3. Plug it into the Pi and wait ~1 minute — RetroPie builds the folder structure automatically.
4. Move the stick back to your PC and copy your ROMs into retropie/roms/<system> (e.g. retropie/roms/snes).
5. Plug it back into the Pi, wait for it to sync, then restart EmulationStation.

Full details in the official RetroPie guide: Running ROMs from a USB drive.

To get a 1:1 ratio on the screen, set your resolution in /boot/config.txt. Exit EmulationStation (Select → Quit → Quit EmulationStation) then run sudo nano /boot/config.txt, or edit config.txt on the boot partition using a card reader (editable in Windows).

• Remove the # before hdmi_force_hotplug=1
• Remove the # before hdmi_group and set it to 2
• Remove the # before hdmi_mode and set it to 87 (custom HDMI mode)
• Add hdmi_cvt=1024 600 60 (or set it to your resolution and refresh rate — this example is 1024×600 @ 60Hz)
• Reboot.

Your final config lines should look like:

hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=87
hdmi_cvt=1024 600 60

Credits: thanks to pixel.red.