Where to Watch Kaiji in the UK

Right now, Kaiji is on Crunchyroll Amazon Channel and several other platforms, sitting at 8/10 on TMDB. Consistently well-regarded, and easy to understand why once you start watching.

Kaiji has the visual identity that makes it immediately recognisable, and the writing to back it up. Kaiji Itou is a good-for-nothing loiterer who spends his days drinking beer and stealing hubcaps—that is, until he ends up being tricked by his former co-worker. Unable to suddenly repay his friend's huge debt all by himself, Kaiji is offered a shady deal to participate in an illegal underground gamble on a cruise ship. This turns out to be nothing more than the beginning of his new life of hell—thrown headlong into a life-threatening roller coaster of mind games, cheating, and deceit. Masato Hagiwara and Fumihiko Tachiki lead a cast that brings real weight to the material. The series ran for 2 seasons (2007–2011), building a story that gave its audience time to invest properly.

Genuinely enjoyable for a wide range of viewers. The animation is the delivery mechanism — the storytelling is what matters.