Jaime has updated his OpenTTD-PSP to Development Version with Multiplayer Support. OpenTTD is a ported version of a clone of ¡°Transport Tycoon Deluxe¡±, not a direct port of the original version. Here is the notice from the author:

I¡¯m glad to announce an available development version which enables wireless play for 1.00 and 1.50 users

This way you will be able to play against other PSP users using same access point or through internet against other unix/mac/windows/PSP users, enjoy.

I¡¯m also hosting two servers "friendly" for PSP users, anyway you can also play on any "normal" pc server, but some of them use custom graphics, huge maps or other features not fully supported on PSP.

Servers are:

OpenTTD for PSP players Europe
OpenTTD for PSP players USA

I have managed to play fine against pc users on a 256x512 map containing 3 companies with 54 trains, 30 planes and 43 road vehicles.

Remember this is a development version, so it could not work as expected, please report any not known issue.

Known issues:

Access point selection interface is nasty
Connection lost, isn¡¯t tolerated
Servers window is to big to fit on screen
It gets disconnected from some high load servers
Doesn¡¯t have keyboard support
Not tested with DHCP connections
Some others i should be forgetting
Usage Notes:

To change your network name, you must edit your openttd.cfg file and change the 'player_name' value
To play this release using wireless you must start it with network switch enabled, or load with switch disabled to play single player.
Most of times you should increase cpu speed by pressing "start + R trigger"
Playing maps bigger than 512x512 isn¡¯t recommended
Poor wireless signal means getting dropped on multiplayer games