From Worms Knowledge Base
Deathmatch is a single player mode that has ranks and uses the Intermediate scheme. Every victory will increase your team's rank, but if the match is a draw or you lose, your rank will decrease. Quitting the game will count as losing, but causing it to crash or otherwise taking the game down will not decrease your rank. The best rank is Elite and the worst is Absolute Beginner.
List of all the Deathmatch ranks:
0. Absolute beginner 1. Beginner 2. Inexperienced 3. Rookie 4. Novice 5. Below average 6. Average 7. Reasonable 8. Above average 9. Fairly competent 10. Competent 11. Highly Competent 12. Veteran 13. Distinguished 14. Highly Distinguished 15. General 16. Major 17. Field Marshall 18. Hero 19. Superstar 20. Elite