Apparently, this game contains a multiplayer feature, which requires the user to enter Amtex 'Derby codes' in order to unlock its functionality. However, no one seems to have ever used it.
This quandry has puzzled many of the game's enthusiasts for over a decade. For example, a forum discussion from 2001 reveals (failed?) efforts to contact Europress about the codes: http://games.groups.yahoo.com/group/computerfishinggames/message/42
On further research, it seems that people have been asking about this as early as January 1996: "[it is] mentioned that you can obtain a derby code from Amtex, see manual for more information" [https://groups.google.com/forum/?fromgroups=#!topic/comp.sys.ibm.pc.games.action/-9eMoZVfCmE]
Can anyone shed further light on this? Presumably, few people ever obtained the code in 1994 and the memory of it got lost over time.