It’s a non official release but Simutrans, using SDL, seems to compile very easily with the AmigaOS 4 SDK, so thanks to thematic’s effort, now Simutrans 102.2.x is available for AmigaOS 4.
You can dowload the binaries of Simutrans at aminet.net. and there’s also a Simutrans Experimental v7.3 version available for downloading here. More details at Simutrans International Forum.