Two Knights vs Lone King = Draw?

It is impossible to force mate with two knights against a bare king.

There are some very specific scenarios where it is possible to mate but generally require the king in the corner to start and often one of the last moves was to take black's last piece/pawn to cause it.

It is possible to happen, but it is impossible to force it.

Okay I see, thanks for the comments!

it's very possible to make it... u'll have to move ur king to restrict his movements... use one knight to block his moves use the other to force mate

With the exception of a few cases where the king is already at the edge of the board, that is incorrect. Mate can't be forced with that material.

Check with any of the online Nalimov tablebases.

but it's quite difficult... very much

you are right Martin... it's going to end in a draw or stalemate

To give you a for-instance: White King on b6, Black King on b8, White Knight on d6 (covering c8), White Knight on c6 (checking). Black King is forced into the corner. But now the d6 Knight has no move that checks a8, so White either makes a meaningless move (and stalemates) or lets Black back out to b8 (and has made no progress).

There's no better square for the d6 Knight because in order to check a8 next move it would have to be able to move from a square that allows it to attack c8 to one that allows it to attack a8. It can't do that in one move because any such squares are of the same colour (and a Knight must change the colour of its square every time it moves). And without the cover on the square c8, the Black King is not forced to go to a8 for the checkmate.

There are other odd positions allowing a two-Knight mate, but none of them can be forced and all can be trivially avoided.

There's no way at all to force mate with two Knights against a bare King (as explained) and it is easy to avoid being mated even when you are forced close to the corner. Just don't go into the corner unless you have no alternative - if that arises you must be let out again or stalemated.

It is possible, but ridiculously hard, to mate with two Knights against a King and pawn provided the pawn is no further forward than the "Troitzky Line" (varies from file to file) as one of the Knights can blockade the pawn until the King is cornered, and then release the pawn to prevent the stalemate. You then need, of course, to deliver the checkmate before the pawn Queens. Don't obsess over this. You could go your whole life and never reach this ending.

Fun stuff!

Unrelated to the question at hand but it might be useful for you to roll back to 58.Nc5 (? in my opinion) and consider how restricted the squares are for Black's king and how you might exploit it.

Something like 58.Kd4 can start pushing the other king backwards like a sumo wrestler (What can Black do now? h5 doesn't appear to work and Kd6 is simply met by Nf7+ where you can afford to drop your knight in exchange for a winning endgame with your King, Pawn and Knight vs King)

Could analyze these lines more but they look promising and worth practicing against a computer for improving technique.  

Some moves ealier you had a pawn plus the two knights. That pawn was your winning chance, so you needed to avoid allowing black to exchange it for one of his pawns even if it would cost you a knight. After all you can win with a knight and a pawn, but you cannot win with two knights and no pawn.

The following puzzle is the position after black's move 60... h5. Here white responded by playing 61. gxh5+. That was a blunder which gave away the win. White does have a winning continuation after black's 60... h5:

Nice! Black has to take the Knight or lose the h-pawn anyway, and White gets a protected passed pawn and can stop the h-pawn at his leisure.

This is brilliant. Very good job analyzing the position because I wouldn't have seen that, thanks for your input! 

ymartino, thank you. You are welcome.

I just had a look at a tablebase to confirm that White can't win after 61. gxh5+ by leaving the last Black pawn on the board. The tablebase has it as drawn, and on a quick check g-pawn is already far beyond the Troitzky line (Knight's pawns are the worst for the side with the two Knights to play against).

...Not that I personally could win a two-Knights ending wherever the pawns were - it was hard enough to get used to the Knight and Bishop ending.

Footnote: The Troitzky line doesn't dictate whether all positions with the pawn beyond it are drawn - but if the pawn is on or behind the line (and the blocking Knight is safe) then a win can be forced no matter where the Kings are. Certain positions are winnable if the pawn is further advanced depending on the King positions.

Thanks for that update Gil. 

Indeed I reached the 2N v P ending in a game vs comp easy about a year ago. From mate in 42, I played 18 perfect moves and blundered, resulting in a 50 move rule.