File openmsx-set-install-location.patch of Package openmsx
diff -Nur openmsx-18.0-orig/build/custom.mk openmsx-18.0/build/custom.mk
--- openmsx-18.0-orig/build/custom.mk 2022-06-12 15:53:09.000000000 +0200
+++ openmsx-18.0/build/custom.mk 2023-04-02 13:19:34.879500395 +0200
@@ -4,7 +4,7 @@
# openMSX is always installed into a single self-contained directory.
# But you can change that directory to for example /usr/local/openMSX
# or /usr/games/openMSX if you like.
-INSTALL_BASE:=/opt/openMSX
+INSTALL_BASE:=/usr/lib/openMSX
# Add revision number to executable file name? This applies only to
# development versions, not to release versions (see version.py).