• Diablo I - https://github.com/diasurgical/devilutionX
• Zelda: Link to the past - https://github.com/snesrev/zelda3
• Metroid II - https://flathub.org/apps/io.github.am2r_community_developers.AM2RLauncher
• Sonic 1/2 - https://github.com/Rubberduckycooly/Sonic-1-2-2013-Decompilation
• SonicCD - https://github.com/Rubberduckycooly/Sonic-CD-11-Decompilation
• GTA3/GTAVC - https://github.com/halpz/re3 (Original project github link not available)
• Papermario - https://github.com/pmret/papermario (US Rom 100% decompiled, but don't have a port yet)

If you use steam, this project https://github.com/luxtorpeda-dev/luxtorpeda, converts proprietary engines to use opensource versions when available. Here: https://luxtorpeda-dev.github.io is a list of games supported by this. How to use Luxtorpeda on Steamdeck: https://www.gamingonlinux.com/2022/03/steam-deck-using-luxtorpeda-for-morrowind-warzone-2100-and-x-com/

• about:config: widget.non-native-theme.scrollbar.size.override, from 0 to however many css pixels wide you want the scrollbar

• user.js: user_pref("widget.non-native-theme.scrollbar.size.override", 5);

Take a look here (base64): aHR0cHM6Ly9yLXJvbXMuZ2l0aHViLmlvL21lZ2F0aHJlYWQvc29ueS8jc29ueS1wbGF5c3RhdGlvbi0y

PS2 section, but there are links to almost every older system (including PS3)

Take a look here: https://r-roms.github.io/megathread/sony/#sony-playstation-2