Round 2...my opponent was unrated and i thought this should be extremely easy...almost paid the price...odd opening from white and afterwards he told me he has been playing online a couple of years now...just never otb tourneys before
Having the advantage and then losing...TWICE

[Event "Ekhuruleni open section A Round 2"] [Site " THS Springs "] [Date "March 24, 2017"] [White "P MDWAMATO "] [Black "MJ FOWLER "] [Result "0-1"] [WhiteElo "UNRATED(1ST TOURNAMENT)"] [BlackElo "1417"] [TimeControl "60/60"] 1. e4 c5 2. h3 Nc6 3. a3 Nf6 4. Nc3 g6 5. d3 Bg7 6. Bg5 d6 7. Nf3 Nd4 8. Bxf6 Bxf6 9. Nxd4 cxd4 10. Nd5 Bg7 11. Qf3 O-O 12. h4 h5 13. Be2 Be5 14. g3 e6 15. Nb4 a5 16. Na2 b5 17. g4 hxg4 18. Qxg4 Bg7 19. h5 e5 20. Qg2 g5 21. h6 Bf6 22. h7+ Kh8 23. O-O-O b4 24. axb4 axb4 25. Kb1 Qa5 26. Qf3 Qxa2+ 27. Kc1 Bg7 28. Rdg1 Qa1+ 29. Kd2 Qxb2 30. Rb1 Qc3+ 31. Kd1 Ra2 32. Rc1 b3 33. Bf1 b2 34. Qe2 bxc1=Q+ 35. Kxc1 Ra1#

When he gave the check on move 17, you should have moved to kh1. When in check like this, there are only a few available options, and they are almost always very controversial, so it is best to calculate them all the way through. I put it into an engine and it says to take the bishop with rook, but to play like a human, the best move is to move Kh1 to avoid the pin. Since you only had 3 legal moves, calculating all of them out would have been the best option. and out of the three, you happened to choose the worst one.
I don't know exactly when you wen't from winning to losing, but just a thought wold be to not have taken on move 19 Nxd5. Yes that pin with your rook hurts, but by taking on d5 you allowed him an zwischenzug to isolate your a and c pawns. I see the idea of a discovered attack on his a rook, but he had time to handle that. Plus you would be down material if he could take the knight when it gives the check.

I played 3 games that I lost while being up queen.
What format? online/otb? bullet?

[Event "Ekhuruleni open section A Round 3"] [Site " THS Springs "] [Date "Mar 25, 2017"] [White "MJ FOWLER "] [Black "S CRONWRIGHT "] [Result "1/2 - 1/2"] [WhiteElo "1417"] [BlackElo "1619"] [TimeControl "60/60"] 1. e4 e6 2. d4 d5 3. Nd2 dxe4 4. Nxe4 Nd7 5. Nf3 Ngf6 6. Bg5 Be7 7. Bd3 Nxe4 8. Bxe7 Qxe7 9. Bxe4 Qb4+ 10. Qd2 Qxb2 11. O-O Nf6 12. Bd3 O-O 13. a3 Qb6 14. Rfe1 c5 15. Rab1 Qc7 16. Re5 cxd4 17. Rg5 g6 18. h4 e5 19. Rxe5 Bg4 20. Rbe1 Bxf3 21. gxf3 Rae8 22. Qg5 Rxe5 23. Rxe5 Nh5 24. Re7 Qd6 25. Rxb7 Qxa3 26. Qe7 Qc1+ 27. Kh2 Qf4+ 28. Kg1 a5 29. Be4 Qc1+ 30. Kh2 Qf1 31. Qg5 Qxf2+ 32. Qg2 Qxh4+ 33. Qh3 Qxh3+ 34. Kxh3 Nf6 35. Bd3 Ra8 36. Bc4 a4 37. Rxf7 Kh8 38. Rxf6 Rc8 39. Bd3 Ra8 40. Kg4 a3 41. Bc4 a2 42. Bxa2 Rxa2 43. Rd6 Rxc2 44. Rxd4 Kg7 45. Rd7+ Kh6 46. Rd1 Rc4+ 47. Kg3 Kg5 48. Rd5+ Kf6 49. Rd6+ Kg5 50. Rd5+ here both of us had around 2-3mins left on our clocks...last game still going in the tournament hall...almost the entire section A watching us blitz it out...i didnt note the rest of the moves due to time trouble but it ended with a draw by insufficient material...he blundered a pawn and i forced a trade of rooks and the remaining pawns...i had no right to draw here but i really tried to get a draw against a higher rated player and was successful

When he gave the check on move 17, you should have moved to kh1. When in check like this, there are only a few available options, and they are almost always very controversial, so it is best to calculate them all the way through. I put it into an engine and it says to take the bishop with rook, but to play like a human, the best move is to move Kh1 to avoid the pin. Since you only had 3 legal moves, calculating all of them out would have been the best option. and out of the three, you happened to choose the worst one.
I don't know exactly when you wen't from winning to losing, but just a thought wold be to not have taken on move 19 Nxd5. Yes that pin with your rook hurts, but by taking on d5 you allowed him an zwischenzug to isolate your a and c pawns. I see the idea of a discovered attack on his a rook, but he had time to handle that. Plus you would be down material if he could take the knight when it gives the check.

the 1st game is not even what the topic is about haha this comes into play on round 4 and 5
oh okay haha, I was just giving some advice over that game

If the OP was white in that game when was he ever winning?
38. Rxf6 can be considered winning by material advantage. it can get tricky with that passed pawn, but hey.

You're practically lost after 9. f4 and certainly lost after 11. d4.
Why would you play 9. f4?
Spend some time understanding just how bad your 9th and 11th moves were so you don't repeat your mistakes and can play the Closed Sicilian better in future.
12. Rf3 was a serious mistake but he didn't take full advantage of it. Too late by that point anyway.
So chalk up that loss to bad opening play. You were never in the game.

If the OP was white in that game when was he ever winning?
38. Rxf6 can be considered winning by material advantage. it can get tricky with that passed pawn, but hey.
I was talking about a different game. The one you posted first. But ya of course the 2nd one black was up 3 pawns and dropped a knight (by Rxf6).
you know it would be nice to know the formats of these games: online/otb? rapid?
If it is OTB, ya I can see, that hurts......

[Event "Ekhuruleni open section A Round 4"] [Site " THS Springs "] [Date "Mar 25, 2017"] [White "P NGIDI"] [Black "MJ FOWLER"] [Result "1-0"] [WhiteElo "1500"] [BlackElo "1417"] [TimeControl "60/60"] 1. e4 c5 2. d3 Nc6 3. Nf3 d6 4. Nc3 Nf6 5. Bg5 e6 6. h3 Be7 7. Bd2 a6 8. a3 b5 9. Na2 Bb7 10. Be2 Nd7 11. c3 Nce5 12. Nc1 Nxf3+ 13. Bxf3 Ne5 14. Be2 O-O 15. O-O d5 16. f4 Ng6 17. e5 d4 18. Bf3 Bxf3 19. Qxf3 Nh4 20. Qe4 Nf5 21. Kh2 Bh4 22. Ne2 dxc3(MY 1ST INACCURACY IIRC )23. bxc3 c4 24. d4 Be7(SHOULD HAVE PLAYED 24...h5 with the idea of 25.g4 hxg4 26.hxg4 Bg3+ 27.Nxg3 Qh4+ but i completely missed it) 25. g4 Nh6 26. Ng3 Re8 27. f5 exf5 28. gxf5 Bf8 29. Bxh6 gxh6 30. f6 Qd7 31. Nf5 Kh8 32. Qf4 a5 33. Rg1 Bxa3 34. Rxa3 Rg8 35. Nxh6 Rxg1 36. Kxg1 Qxh3 37. Qg5 Resigns...i am not proud of this game...my engine has the advantage at -1.5 here at a point...i have no excuse but terrible play in this game

Your game vs Mthunzi
You're practically lost after 9. f4 and certainly lost after 11. d4.
Why would you play 9. f4?
Spend some time understanding just how bad your 9th and 11th moves were so you don't repeat your mistakes and can play the Closed Sicilian better in future.
12. Rf3 was a serious mistake but he didn't take full advantage of it. Too late by that point anyway.
So chalk up that loss to bad opening play. You were never in the game.
That was wise words!