Not sure if this fits the bill perfectly, but my most proud creation in a game definitely is bringing my board game Trivia Throne to Tabletop Simulator (find it on the Steam Workshop)!

Relay Challenge "Formidable Enemy" - Hitman 2: Silent Assassin - Russian Soldiers

Relay Challenge "Mythical Beast" / Dragon's Dogma 2 / Harpies / I'm really happy with the minimalistic composition of this one!

Relay Challenge - Hitman 2