GRFs are small extensions to OTTD's graphics. A GRF could be a new bridgetype, a whole new trainset or a new cargo type. #openttdcoop is using a compilation of GRFs to make our gameplay even more addictive.

Brianetta provides a nice collection of GRFs which are applied to our games. You may get this set and some information at his info-page.

Taken from Brianetta's page you'll need these GRFs to play:

[newgrf]
pb_ukrs.grf
pb_hovs_bus.grf
pb_viaduct.grf
basic_platformsw.grf
harbourw_456.grf
jcindstaw.grf
newstatsw.grf
pgs-counw.grf
pgs-freiw.grf
pgs-silvw.grf
pgs-subuw.grf
ukwaypointsw.grf
usstatsw.grf