JGR's Patchpack

JGR's Patchpack is Jonathan Rennison's long-running fork of OpenTTD. It is a different executable you install next to vanilla OpenTTD, not a NewGRF, AI, or Game Script. Multiplayer requires every player on the same jgrpp version; vanilla clients cannot join a patchpack server.

The extra surface is large: programmable signals, more flexible stations, extra map sizes and height levels, cargo dest, improved logic for breakdowns and infrastructure, and a pile of smaller UI and construction tools the trunk game has not taken. Savegames are not a free round-trip with vanilla — treat it as its own game with OpenGFX/OpenSFX (or original TTD baseset files) the same way you would stock OpenTTD.

PlayBound installs the 64-bit Windows zip from JGRennison/OpenTTD-patches. macOS ships a universal dmg on the same tag; Linux has distro packages and a generic tarball. OpenGFX downloads on first run when no original graphics are present.