In the World Youth Championships in 1975 Tjentište Christiansen became vice - world champion. 1977, the grandmaster title he was awarded by FIDE. Three times he won the U.S. Championship: 1980, 1983 and 2002, also three times he won the U.S. Open. Twice he succeeded in qualifying for the Interzonal, in which he in Moscow 9, 1987 in Szirák 8 in 1982. From 1980 to 2002 he played for the U.S. in nine Chess Olympiads. The U.S. team won one silver and four bronze medals.
In 1979 he won the Tournament of Linares tradition before Viktor Korchnoi. Two years later he won a split ( with world champion Anatoly Karpov ) first place. Christiansen won major tournaments in Cologne 1988, Wiesbaden 1994, Reykjavík 1998 Food 1999. In the 1990s, he also played in the chess Bundesliga for the SG Porz. Here he scored in the 1990/91 season at board 2 a score of 12 out of 13
Christiansen is considered tactics stressed attack players. He published a number of chess books and is a highly respected commentator for the Internet Chess Club, where he delivers at irregular intervals audio commentary of live webcasts with top international tournaments. His current Elo rating is 2575 (as of October 2007). His previous highest Elo rating was 2625 in July 1992. Christiansen is married to Natasha (born 1962 ), a chess player.
- Alekhine 's Defense As White, The Four Pawns Attack. Thinkers ' Press. Davenport, Iowa in 1989. ISBN 0-938650-43-2. ( with Robert Rain Gruber and Joseph Manuel )
- Dutch defense, Hamburg: ET The Chess Archives Rattmann, 1990.
- Storming the barricades. Gambit Publications, London, 2002. ISBN 1-901983-82- X.
- Rocking the ramparts: a guide to attacking chess. Batsford, London, 2003. ISBN 0-7134-8776-3.