Nimzovich was a positional mastermind, giving rise to the hypermodern school of chess theory that contends control of the center is more important than occupying it. In this way, one can use pieces rather than pawns to control key squares in the center (like e4 in the Nimzo/Queen's Indian). But his generalizations were also backed up by a sharp tactical mind. Let's look at this classic that demonstrates the latter point, Nimzovich-Alapin (Riga, 1913).
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. exd5 Nxd5 (starting off as a harmless exchange French)
5. Nf3 c5 (looking for immediate equality in the center) 6. Nxd5 Qxd5 (rather than accept an isolated pawn) 7. Be3 cxd4 8. Nxd4 (and now we notice where Black's maneuvers have left him a little underdeveloped and exposed)
8...a6 9. Be2 Qxg2? (hand in the cookie jar...) 10. Bf3 Qg6 11. Qd2 e5 (to get rid of the d4 knight...) 12. O-O-O! (or not) exd4 13. Bxd4 Nc6 (White is down a piece, but his development advantage is large. How to bring this one home?)
14. Bf6!! If you saw this coming you've either seen the game before, or you should say hi in the comments section, Mr. Kasparov!
14...Qxf6 15. Rhe1+ (move 15 in the exchange French, and it's already time to roll up the vinyl board) 15...Be7 16. BxN+ Kf8 (trying to avoid immediate mate but...) 17. Qd8+! Bxd8 18. Re8#
I've played games like this before, but only from the losing side.