Deathworld

"Deathworld" (1960) is a science fiction novel about a gambler, by Harry Harrison.

Excerpt:
Some planet in the galaxy must - by definition - be the toughest, meanest, nastiest of all. If Pyrrus wasn't it... it was an awfully good approximation! JASON dinALT sprawled in soft luxury on the couch, a large frosty stein held limply in one hand. His other hand rested casually on a pillow. The gun behind the pillow was within easy reach of his fingers. In his line of work he never took chances. It was all highly suspicious. Jason didn't know a soul on this planet. Yet the card sent by service tube from the hotel desk had read: Kerk Pyrrus would like to see Jason dinAlt. Blunt and to the point.