From #openttdcoop wiki
Cooperation + Competition = Coopetition
The term Coopetition stands for the idea of bringing a competitional challenge into our cooperative gameplay.
- Two players team up and play versus another team.
- A dedicated server will be set up for this challenge - besides the 4 players, only visitors are allowed - the visitors should not talk anything helpful for a team. The Server will run on a Nightly version of Openttd, without any additional GRFs loaded.
- The game will begin at a previousely settled date/time.
- The playing time is limited to 8 years (~2 hours). The game will take place from 1959 - 1967 to make upgrading of locos necessary.
- Each team may use a voicecom like Ventrilo or Skype to improve its communication. Its all up to the team. #openttdcoop has some Teamspeak-Channels for this purpose - you may use it, if you want.
- A random map will be played.
- In the end, the train income and running costs matters. At the beginning of year 1968 the game will be paused and a screenshot of the budgets will be taken. The net income, calculated by train income minus train running costs will be the key figure.
- Don't play destructive - play competitive! Do anything you want to decrease your opponent's profit - but remember: play fair!
- No buying of transportation rights. Furthermore, do not use known OTTD-bugs for your purposes.
- If the other team demands you to change parts of your tracks so they can bridge/tunnel etc - help them! Competition doesn't mean ruthlessness!
- Build your lines in a way the opponents can bridge / tunnel them - which means: place your lines right next to each other. Do not necessarily built large parts of your tracks on sea-level.
- Don't use "station walk" - use feeders instead.
- Have fun!
View the Settings in the .cfg here