Hype Train

A Hype Train starts when paid support arrives fast enough inside a short window, then climbs through levels as more support lands before the timer expires. Each level unlocks rewards for the chat, usually temporary emotes, and a progress bar sits in front of everyone watching. The design turns scattered individual purchases into a shared goal, which is why chats start coordinating to push one more level.

It is a Twitch feature. YouTube live has its own paid mechanics in Super Chat, Super Stickers and gifted memberships, without the stacked group event on top, so anyone moving between the two should not expect a like-for-like equivalent.