I have not read the manga, so I will judge this purely based on the anime. This is pretty much the bog-standard death game anime you would see bouncing around the seasonal charts a decade ago (with art and animation quality to match). What makes this somewhat more intriguing is the mystery element - whereby the participants in the death game appear to be recruited as part of a broader conspiracy, instead of having straightforward goals and defined rules from the get-go. This mystery is used to a decent effect to drive tension in the early episodes but unfortunately fades over the course of the show's runtime in favor of more bombastic action setpieces and hastily written and poorly executed character backstories.
Speaking of, I would highlight Akira, the MC, as the standout character in the series. Sure, he isn't anything too unique as far as death game MCs go (and at the very least he isn't a sigh-inducing weakling or idiot as these MCs tend to be). His aptitude for tactical and strategic thinking makes the "big brain" moments in the show's climaxes entertaining to watch. The way he uses his unique ability to gain an edge over the various enemies he encounters is a consistent highlight of the show. Unfortunately, the more mysterious elements of his own backstory receive no attention during this anime's runtime, but I am satisfied with what we got. The other characters are rather bland and uninteresting, and the villains are comically evil with uninspiring backstories. There are slivers of romance in this anime, especially in relation to the female lead, Yuuri, but it never takes away from the core narrative of the show (which I appreciate). Yuuri is plays a more important role as a critical part of Akira's plans, and her spunky personality forms a good complement to Akira's otherwise stoic persona. The focus is directed towards the action and Akira's thought process, from which where most of the show's core entertainment value is derived.
There isn't too much to comment on from a technical standpoint. The art and animation aren't anything to write home about, with terrible CG used during demanding portions of certain action sequences. The music was mostly forgettable, though the OPs and EDs were catchy and fit the theme of the anime well (though I would probably forget them by the time next season rolls around).
All in all, Deatte 5-byou de Battle was a bit of nostalgic fun, a throwback to the heyday of death games in the early 2010s, and a fresh change of pace from the isekai drab that muddies every season these days. You would get some enjoyment out of it if you prefer more "brain" than "brawn" in your survival games. If you are getting bored of the style of anime we are getting these days, this could be worth a casual watch if you can make room for it on a crowded seasonal watchlist. But if you really wanted a good survival game/battle royale anime to scratch that particular itch of yours, I would recommend checking out classic examples of the genre which have stood the test of time, and potentially some more interesting ones in upcoming seasons.
