There were lot of interesting exotic chess variants that were available to play at jocly.com/#/about till Wednesday, 24 October 2018 when that website was shut down due to confiscation of game server by attackers.
It is still possible to play 2 player human games of those exotic chess variants at jocly.jcfrog.com/joclymatch/gamespanel.php without any of those games recorded to the game server or against very weak AI.
Earlier this year, jocly.com/#/about got open again but it is impossible to connect to game server to review old played human games or to play new human games, let alone play against very weak AI.
If developers like any of these exotic chess variants, then they could be implemented at www.pychess.org for playing 2 player games or as tournaments.
I know implementing the game engine is a lot of hard work and the website is heavily AI based. So, may be in the long run.
Hexagonal chess variants:
1. Glinski chess is the most symmetric and most natural, but there are also 2. Shafran chess, 3. McCooey chess, 4. Brusky chess and 5. De Vasa chess (Parallelogram chess with hexagonal tiling)
Circular chess variants:
6. Modern circular chess and 7. Byzantine chess (with Shatranj pieces)
3D chess variants:
8. Raumschach and 9. 3D chess
Other special board chess variants:
10. Cylinder chess, 11. Rollerball chess and 12. Cubic chess (360 chess authoring)
Rectangular chess variants with interesting fairy chess pieces:
13. Wildebeest chess, 14. Reformed courierspiel, 15. Courier chess, 16. Musketeer chess and 17. Sim chess
(excluding 12 × 12 Metamachy and 14 × 10 Duke of Rutland chess given that the current game engine does not yet support chess boards larger than 12 × 10)
Rectangular chess variants which can be implemented with current game engine:
18. Janus chess, 19. Chancellor chess, 20. Modern chess and 21. Romanchenko's chess
Rectangular chess variants which need implementation of Amazon, which is used in none of the chess variants at www.pychess.org so far, except for Musketeer chess under development as dragon:
22. Tutti-Frutti chess, 23. Gustav III chess, 24. Hyderabad decimal chess, 25. Kaiserspiel, 26. Sultanspiel and 27. Amazon chess
(In Musketeer chess, may be centaur could be weaker and good substitute than very powerful amazon and may be also for instead of the lion in Metamachy)
28. Antichess 960 may be interesting to play, but not making much difference from their unshuffled home rank pieces variants may be 29. King of the Hill 960, 30. Three check 960 and 31. Horde 960
32. Extinction chess may be interesting to be tried out. First player whoever loses either their king or queen or 2 rooks or 2 bishops or 2 knights or 8 pawns loses the played game.
Extinction chess is available for play at greenchess.net/, I think. It is a website that is not as interesting as www.pychess.org, with no tournament facilities or features.
It is still possible to play 2 player human games of those exotic chess variants at jocly.jcfrog.com/joclymatch/gamespanel.php without any of those games recorded to the game server or against very weak AI.
Earlier this year, jocly.com/#/about got open again but it is impossible to connect to game server to review old played human games or to play new human games, let alone play against very weak AI.
If developers like any of these exotic chess variants, then they could be implemented at www.pychess.org for playing 2 player games or as tournaments.
I know implementing the game engine is a lot of hard work and the website is heavily AI based. So, may be in the long run.
Hexagonal chess variants:
1. Glinski chess is the most symmetric and most natural, but there are also 2. Shafran chess, 3. McCooey chess, 4. Brusky chess and 5. De Vasa chess (Parallelogram chess with hexagonal tiling)
Circular chess variants:
6. Modern circular chess and 7. Byzantine chess (with Shatranj pieces)
3D chess variants:
8. Raumschach and 9. 3D chess
Other special board chess variants:
10. Cylinder chess, 11. Rollerball chess and 12. Cubic chess (360 chess authoring)
Rectangular chess variants with interesting fairy chess pieces:
13. Wildebeest chess, 14. Reformed courierspiel, 15. Courier chess, 16. Musketeer chess and 17. Sim chess
(excluding 12 × 12 Metamachy and 14 × 10 Duke of Rutland chess given that the current game engine does not yet support chess boards larger than 12 × 10)
Rectangular chess variants which can be implemented with current game engine:
18. Janus chess, 19. Chancellor chess, 20. Modern chess and 21. Romanchenko's chess
Rectangular chess variants which need implementation of Amazon, which is used in none of the chess variants at www.pychess.org so far, except for Musketeer chess under development as dragon:
22. Tutti-Frutti chess, 23. Gustav III chess, 24. Hyderabad decimal chess, 25. Kaiserspiel, 26. Sultanspiel and 27. Amazon chess
(In Musketeer chess, may be centaur could be weaker and good substitute than very powerful amazon and may be also for instead of the lion in Metamachy)
28. Antichess 960 may be interesting to play, but not making much difference from their unshuffled home rank pieces variants may be 29. King of the Hill 960, 30. Three check 960 and 31. Horde 960
32. Extinction chess may be interesting to be tried out. First player whoever loses either their king or queen or 2 rooks or 2 bishops or 2 knights or 8 pawns loses the played game.
Extinction chess is available for play at greenchess.net/, I think. It is a website that is not as interesting as www.pychess.org, with no tournament facilities or features.