Across:
   6. As iceman melted, he could remember nothing (8)
   8. Order to rage on? (6)
  10. Things our century provided well perhaps (6)
  11. Tic tac toe players joined van with three gamers heading west; thus they made Odyssey with forerunner of 4 (8)
  12. Submit detail of pill (5)
  14. Each season, how US player 18 for 17? (9)
  17. Some sense 'M' aged, a crank regressing to 1942 Defender and Street Fighter perhaps? (6 5)
  20. The French replaced where French absurdly precious (so precious!) (9)
  21. Beat a rival providing 4 maker (5)
  23. Highly considered defence in gymkhana polo: giants ... (8)
  25. ... sent in, knocked out ... what a game! (6)
  27. Outward signs of slightly zany galaxy when heavenly bodies align (6)
  28. Developed nice herd with increased potency (8)
Down:
   1. Ram limo in crash... not ideal! (7)
   2. Close of inn early (4)
   3. Movies, the ultimate filler for strange void (5)
   4. Stink as Australian neighbour holding 16 in one of the first 17 (4)
   5. During idyl, bong is raised in a disgraceful way (7)
   7. One of the first 17 with speed now measured in GHz? (8 5)
   9. Awe as some Inca maze mentioned (9)
  13. Supply Ric all your parts with nice sound (9)
  15. You might do this if you have sown rotten pear! (4)
  16. Focus of 25 dance (4)
  18. School starter upset, say, and coughs up at the outset (7)
  19. Beginner perhaps painting upside down in extreme case (7)
  22. Opening with background feature of 7 ahead of time (5)
  24. Timeless, dynamic, gutsy fellows (4)
  26. Steal from Santa? (4)