A KIA from long ago
I used to play the King's Indian Attack as White by transposing to it from either the French Defense or the Sicilian. Here is a game from that era that was a tremendous fight. Black sacrificed a piece and obtained an initiative that lasted for many moves, only to watch it evaporate in time pressure.
The error on move 50 ended the game quickly, where it might well have gone another 50 moves!
Be sure to use to move list to see the anotations and unplayed variations.