| Octago (Yvio) | Reiner Knizia | Public Solution GmbH | 2008 | reportDE (26.07.2012) by Walter | 5.0 |
| Oddville | Carlo Lavezzi | What's Your Game? | 2012 | reportDE (14.02.2013) by Walter | 4.8 |
 Odin | Yohan Goh,
Hope S. Hwang,
Gary Kim | Helvetiq | 2024 | reportDE (16.10.2024) by Walter | 8.0 |
| Ogallala | Rudi Hoffmann | Altenburger Spielkartenfabrik | 1989 | reviewDE (31.08.2005) by WalterreportDE (31.08.2005) by Walter | 4.4 |
| Oh My Goods! | Alexander Pfister | Lookout Games | 2015 | reportDE (02.09.2017) by Walter | 4.3 |
| Ohanami | Steffen Benndorf | Nürnberger Spielkarten | 2019 | reportDE (20.02.2019) by AaronreportDE (13.02.2019) by Walter | 5.5 |
| Ohne Furcht und Adel | Bruno Faidutti | Hans im Glück Verlag | 2000 | reportEN (31.08.2002) by AaronreportEN (20.08.2002) by Peter | 7.4 |
| Öl für uns alle | Tord Hasselquist | Ravensburger Spieleverlag | 1976 | reportEN (11.09.2002) by Aaron | 2.2 |
| Old London Bridge | Leo Colovini,
Gabriele Bubola | Queen Games | 2022 | reportDE (11.01.2023) by Walter | 5.0 |
| Oltre Mare | Emanuele Ornella | Mind the Move | 2004 | reviewDE (17.11.2004) by Walter | 7.8 |
| Olympos | Philippe Keyaerts | Ystari | 2011 | reportDE (28.12.2011) by Walter | 7.3 |
| Olympus | Andrea Chiarvesio,
Luca Iennaco | Fantasy Flight Games,
Heidelberger Spieleverlag | 2010 | reportDE (09.08.2013) by WalterreportDE (04.08.2013) by Aaron | 7.0 |
| On The Cards | Sebastian Bleasdale | Surprised Stare Games | 2011 | reportDE (16.02.2012) by Walter | 4.8 |
| On the Road | Leo Colovini,
Gabriele Bubola | Helvetiq | 2023 | reportDE (10.07.2024) by Walter | 5.0 |
| On The Underground | Sebastian Beasdale | JKLM Games | 2006 | reviewDE (02.09.2007) by WalterreportDE (18.07.2007) by WalterreportDE (17.01.2007) by Walter | 6.3 |
| Once Upon A Time | James Wallis,
Andrew Rilstone,
Richard Lambert | Atlas Games | 1993 | reportEN (09.12.2003) by Aaron | 4.7 |
| One Week Ultimate Werewolf | Ted Alspach,
Akihisa Okui | Bézier Games | 2018 | reportDE (15.05.2019) by Walter | 3.3 |
| Opera | Hans van Tol | HUCH & friends,
The Game Master | 2009 | reportDE (11.02.2010) by Walter | 7.0 |
| Ora et Labora | Uwe Rosenberg | Lookout Games | 2011 | reportDE (19.01.2012) by WalterreportDE (05.01.2012) by Walter | 6.5 |
| Orcz | Christian T. Petersen,
Greg Benage | Fantasy Flight Games | 2000 | reviewDE (31.12.2001) by Moritz | 6.0 |
| Order Overload Cafe | Jun Sasaki | Oink Games | 2022 | reportDE (27.09.2023) by Walter | 4.0 |
| Oregon | Åse Berg,
Henrik Berg | Hans im Glück Verlag | 2007 | reportDE (08.05.2008) by Walter | 4.2 |
| Origins of World War II | James F. (Jim) Dunnigan | Avalon Hill | 1971 | reviewDE (31.12.2001) by Moritz | 4.0 |
| Orléans | Reiner Stockhausen | dlp Games | 2014 | reportDE (26.03.2015) by Walter | 6.5 |
| Otys | Claude Lucchini | Libellud,
Pearl Games | 2017 | reportDE (23.02.2018) by WalterreportDE (17.02.2018) by Walter | 6.0 |
| Outpost | James Hlavaty,
Tim Moore | TimJim Games | 1991 | articleDE (07.05.2003) by WalterreportDE (29.01.2003) by WalterreportEN (29.01.2003) by Walter | 6.4 |
| Overthrone | Frank DiLorenzo,
Stacey Merrill | R&R Games | 1999 | reviewDE (01.10.2001) by Moritz | 4.7 |
| Ozeanien | Klaus Teuber | Klaus Teuber Classics | 2004 | reviewDE (11.11.2004) by Peter | 2.0 |