I suspect video games use UDP for the same reasons bidirectional real-time communications protocols (WebRTC, VoIP, etc) use them. Generally speaking when you h

I suspect video games use UDP for the same reasons bidirectional real-time communications protocols (WebRTC, VoIP, etc) use them. Generally speaking when you have an interactive session with > 1 parties (especially humans) when/if packet loss or out of order packets occur there's no reason to attempt re-transmission because the clock, people, and application continually move forward in time. Consider a VoIP call - by the time a packet is retransmitted the conversation has moved on. Most audio codecs and implementations have a default packetization interval of 20ms of audio per packet so this is pretty granular. This has been mitigated somewhat with audio codecs like Opus that have packet loss concealment and forward error correction techniques that provide relatively high robustness to this issue. Variable latency (jitter) and out-of-order packets are typically handled by dynamic jitter buffers on each receiving side that can detect when the finely-clocked streams are wobbling. They then buffer incoming frames, potentially with re-ordering, and play them out smoothly with the side-effect being slightly higher latency to perform this (that's why they're dynamic).