I want to run Undertale via Heroics Games Launcher but I get the error: ./runner: error while loading shared libraries: libz.so.1: cannot open shared objects file: No such file or directory.
I tried reinstalling zlib, pacman -Syu and reinstalling the Game.
For anyone having issues: lib32-openssl-1.0 is removed from the arch repos but its available in the AUR.
Multilib packages aren't installed by default just by enabling the multilib repo, so yes you need to find the lib32 libraries your application needs and install them by hand.