Nightmare World is a Manga/Manhwa/Manhua in english language, Shounen series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

One mistake made the future a wasteland rampant with beasts; another mistake made the bloody heroes turn the tide. The wild sand, the sea of ​​the beast, and struggles of humanity, which one is the real enemy of the travellers, or are the enemies already laughing at you in the sky...