| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 1. R Koster vs B Holtrop |
| 1-0 | 10 | 2000 | Zwolle Open | A45 Queen's Pawn Game |
| 2. R Koster vs F Erwich |
| ½-½ | 26 | 2000 | Zwolle Open | E17 Queen's Indian |
| 3. R Koster vs A Wirig |
| ½-½ | 60 | 2000 | Limburg op U18 | A38 English, Symmetrical |
| 4. R Koster vs Baklan |
| 0-1 | 41 | 2000 | Abihome Open | A04 Reti Opening |
| 5. R Koster vs O van Veen |
| 0-1 | 31 | 2001 | NED-ch U20 | A13 English |
| 6. Vladimirov vs R Koster |
| 1-0 | 53 | 2001 | Lausanne Master Open | D87 Grunfeld, Exchange |
| 7. S Burenkov vs R Koster |
| 0-1 | 38 | 2001 | Glorney Cup | B32 Sicilian |
| 8. K Demoyer vs R Koster |
| ½-½ | 33 | 2001 | Glorney Cup | B40 Sicilian |
| 9. R Koster vs J Sedlacek |
| 0-1 | 44 | 2001 | Glorney Cup | E06 Catalan, Closed, 5.Nf3 |
| 10. R Martyn vs R Koster |
| 0-1 | 40 | 2001 | Glorney Cup | D82 Grunfeld, 4.Bf4 |
| 11. R Koster vs A Wirig |
| 0-1 | 50 | 2001 | Glorney Cup | A56 Benoni Defense |
| 12. A Galkin vs R Koster |
 | 1-0 | 23 | 2001 | Essent Open | B45 Sicilian, Taimanov |
| 13. R Koster vs R Potze |
| 1-0 | 39 | 2001 | Essent Open | D83 Grunfeld, Grunfeld Gambit |
| 14. S Guliev vs R Koster |
| 1-0 | 24 | 2001 | Essent Open | D85 Grunfeld |
| 15. R Koster vs P Hulshof |
| 0-1 | 58 | 2001 | Essent Open | E67 King's Indian, Fianchetto |
| 16. K Rooda vs R Koster |
| ½-½ | 25 | 2001 | Essent Open | D75 Neo-Grunfeld, 6.cd Nxd5, 7.O-O c5, 8.dxc5 |
| 17. R Koster vs M de Mie |
| ½-½ | 31 | 2001 | Essent Open | A13 English |
| 18. H Plasman vs R Koster |
| 0-1 | 27 | 2001 | Essent Open | B32 Sicilian |
| 19. R Koster vs A Vuilleumier |
| 1-0 | 51 | 2001 | Essent Open | E97 King's Indian |
| 20. R Koster vs Z Peng |
| 0-1 | 45 | 2001 | Essent Open | A25 English |
| 21. S Ernst vs R Koster |
| ½-½ | 30 | 2001 | Groningen SO-ON | D85 Grunfeld |
| 22. J Jens vs R Koster |
| 1-0 | 46 | 2001 | Groningen SO-ON | C18 French, Winawer |
| 23. R Koster vs J Jens |
| 0-1 | 20 | 2002 | NED-ch U20 | E00 Queen's Pawn Game |
| 24. S Williams vs R Koster |
| ½-½ | 44 | 2002 | Smith & Williamson YM 12th | A30 English, Symmetrical |
| 25. R Koster vs E Belle |
| 1-0 | 51 | 2003 | Groningen Harmonie op-A | E06 Catalan, Closed, 5.Nf3 |
Kibitzing
