I was testing out the classic compile version of Mayhem 7.7, and it is playing very strange moves. It will leave pieces en prise, which shouldn't happen even at a search depth of 1. The other compiles are fine; classic is the only one that acts odd. Below is a sample PGN file from a game I played in the Arena GUI. Notice on move 10 that Mayhem doesn't even move an undefended bishop that is attacked. I pasted the log file for this game at https://pastebin.com/xn2BYbL2 as Github didn't like some of the characters that were contained in the log file.

[Event "Computer chess game"]
[Site "TOSH-PC"]
[Date "2022.11.26"]
[Round "?"]
[White "Mayhem 7.7 x86 windows classic 64bit"]
[Black "TonysChess004r31"]
[Result "0-1"]
[BlackElo "2000"]
[ECO "A45"]
[Opening "Trompowsky"]
[Time "14:58:44"]
[Variation "2...Ne4 3.Bf4 c5 4.f3 Qa5+ 5.c3 Nf6 6.d5"]
[WhiteElo "2000"]
[TimeControl "40/60:40/60:40/60"]
[Termination "normal"]
[PlyCount "44"]
[WhiteType "program"]
[BlackType "program"]

1. d4 {(d2-d4) 0.00/1} Nf6 2. Bg5 {(Bc1-g5) 0.00/1} Ne4 3. Bf4 {(Bg5-f4)
   0.00/1} c5 4. f3 {(f2-f3) 0.00/1} Qa5+ 5. c3 {(c2-c3) 0.00/1} Nf6 6. Nd2
   {(Nb1-d2) 0.00/1} cxd4 7. Nb3 {(Nd2-b3) 0.00/1} Qd8 8. cxd4 {(c3xd4)
   0.00/1} e6 9. g4 {(g2-g4) -0.13/7 1} Nd5 {(f6d5 f4g3 d5e3 d1d3 e3f1 e1f1
   d7d5 f1g2 b8c6) +0.95/9 1} 10. Nd2 {(Nb3-d2) -0.22/7 1} Nxf4 {(d5f4 h2h4
   b8c6 e2e3 f4d5 d1e2 f8b4 a2a3 b4d6) +4.37/10 1} 11. Qc2 {(Qd1-c2) -0.28/7
   1} Nc6 {(b8c6 e2e3 d8h4 e1d1 f4g6 d2e4 d7d5 f1b5 c8d7 e4g3) +4.94/10 1} 12.
   Rc1 {(Ra1-c1) -0.33/5 1} Qh4+ {(d8h4 e1d1 f4d5 c2e4 h4f2 d1c2 d5b4 c2b1
   d7d5 e4f4 c6d4) +6.13/9 1} 13. Kd1 {(Ke1-d1) -0.33/1} Nd5 {(f4d5 c2e4 h7h5
   d2c4 h5g4 e4g4 c6d4 e2e3 h4f2 g4d4 f2f1 d1c2) +5.79/9 1} 14. Qb3 {(Qc2-b3)
   -0.30/6 1} Qf2 {(h4f2 c1c3 c6d4 g1h3 f2h4 b3c4 d5c3 b2c3 d4c6 d1c1)
   +6.99/10 1} 15. a4 {(a2-a4) -0.31/5 1} Ne3+ {(d5e3 b3e3 f2e3 c1c3 e3d4 d1e1
   d4a4 f1g2 f8b4 c3c1) +12.33/10 1} 16. Qxe3 {(Qb3xe3) -0.31/1 0} Qxe3 {(f2e3
   c1c3 e3d4 d1e1 d4a4 c3c1) +12.58/11 1} 17. Rc2 {(Rc1-c2) -0.43/6 2} Bb4
   {(f8b4 d2e4 c6d4 c2c3 b4c3 b2c3 d4c6 f1g2 e8g8 d1e1) +13.58/11 1} 18. d5
   {(d4-d5) -0.47/6 2} Nd4 {(c6d4 d5e6 d7e6 g1h3 d4c2 d1c2 e3d2 c2b3)
   +16.01/12 1} 19. dxe6 {(d5xe6) -0.58/6 2} dxe6 {(d7e6 g1h3 d4c2 d1c2 b4d2
   h3f2 c8d7 f2e4 a8c8 c2b1 c8c1 b1a2 d7a4 e4d2 e3d2) +16.58/11 1} 20. Rxc8+
   {(Rc2xc8+) -0.71/5 2} Rxc8 {(a8c8 d2c4 c8c4 g4g5 c4c1) +M3/13 1} 21. Nc4
   {(Nd2-c4) -104.85/4 0} Qb3+ {(e3b3 d1c1 b3c2) +M2/12 1} 22. Kc1 {(Kd1-c1)
   -104.85/1} Qc2# {(b3c2) +M1/12 1} 0-1