This art has some references to Katana Zero's poster

Barney Zombie

Hazardous Environment Combat Unit BF

Mr Crowbar Man

m̵̶̴̛̬̗̯̟̰̪̱͙͉͇̉ͩ̎ͩͫͫ̌̏̃̃͢͠ǫ̴̛͕̗̣͔̗̩̞̘͈̺̥̎ͩ̐̄͒̋̆͊͊͠͠͡g̷̨̢̨̯̫̙̖̱̼̮̮̹̥̦̦̫͛͆ͤͩ͌̆͆͋̒̌̕͘͞͞͝e̡̖̩̜̮̪̳̪͚̩̙͋̓̇́ͦ̒̈́̎̆̓͜͡-̶̡̢͇̤̣̹̼̼̦̯̻͗͆ͨ̎̄̇͐̓ͨͩ̋͝k̶̢̡̧̯̹̱̭̣̩̼̠̟ͣͤ̄̈̆̇̐͒ͯ̐͆͋͜͝o͇̲͍̦͇̞̹ͮͯ̊͂ͬ́̑̓̓͜͝͝͏̘̠̙̗̋ͫ̓ͬ̔͐̓̍͆̉ͦ͢v͈̤̳̪̲̩͎́ͫ̔͛̂͋̿̌͛̇̊̋̑͒̊͛̇ͬͅ ̬̘̀̿ͮ͐͘͏̵̵͈͎̆ͬͫͤ̓ͫ̈́͌̇ͦͪ̈́͢͜

Solar Flare 🔥🔥🔥

war correspondent Paci Perkins

Many parts of the United States of Diavolo were designed with reference to City 17 in Half Life 2 Beta

Drew Gordon Freeman! :D

PTTR