The Hunger Games?

Btooom!

i recommend it.... has good story and still on-going right now...

I second Btooom!, really similar to Battle Royale except instead of high schoolers, its adults. Theres still a hot highschool girl though ^^.

I strongly second 7 Seeds. The views some people here to have of it ... don't match up with what I remember reading at all. If you want a Battle Royale vibe, there really isn't anything closer to it than one of the later arcs.
If it helps at all - there are multiple protagonists and the characters of the first few volumes aren't who the story spends the most time with.

I second 7 seeds and Bio Meat: Nectar.

While I understand your reticence when reading 7 seeds, I found it very good later on (better sense of mystery than in BR, but less psychological tension)...

Bio Meat's premise was great (one of the rare times I read a decent S-F plot in a manga) and while the character's personalities are a bit too much "shounen-ish", it's a nice read and the 2d part (when the heroes are all adults) was a great final.

I'll add Jisatsutou, the premise sounds a bit lame or maybe too depressing, but it gets better after a few chapters when the protagonist finds some courage.

Aphorism
Cry Eye
Kamisama no Iutoori (FUJIMURA Akeji)
La Mosca
Duds Hunt
Mirai Nikki

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Ten of thousand soldier are worth less then 1 high rank officer on the battlefield