Of those mentioned. OpenChess is completely free. Hiarcs is probably the best commercial Palm chess game. Miniature was a big disappointment. Eboard is not that good for viewing games.

All in all, Nokia is still an astonishingly poor environment for chess players. It someone was going to make an actually good chess game for the N900, they should either start with Scid (for its many useful functions) or Miniature (for its beauty and mostly unrealized potential).