This is a wide field; there are so many critical positions;
@TN
I´m sure you´ve a proper overview of all systems, maybe you could give the critical games to the subsystems I mention below to have a starting point?!
#1:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. exf6
#2:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Bg3
#3:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Nxg5 hxg5 10. Bxg5 Be7 11. exf6 Bxf6 12. Be3
#4:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Nxg5 hxg5 10. Bxg5 Nbd7 11. g3 Rg8 12. h4 Rxg5 13. hxg5 Nd5 14. g6 fxg6 15.Qg4 Qe7
#5:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Nxg5 hxg5 10. Bxg5 Nbd7 11. exf6 Bb7 12. g3 c5 13. d5 Nxf6 (13... Bh6) (13... Nb6)
#6:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Nxg5 hxg5 10. Bxg5 Nbd7 11. exf6 Bb7 12. g3 c5 13. d5 Qb6 14. Bg2 O-O-O 15.O-O b4 16. Na4
# 7:
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Nxg5 hxg5 10. Bxg5 Nbd7 11. exf6 Bb7 12. g3 c5 13. d5 Qb6 14. Bg2 O-O-O 15.O-O b4 16. Rb1