I read this novel about 20-25 years ago. I read it in French. Of course it might have been a translation, but for some reason I cannot put my finger on, I think it was a French original. I also have a vague memory that it was long enough for two paperback volumes.
It is a dystopia where the world is divided into two blocks. The Eastern block is very poor, and it is very hard but just possible to cross the border to the West. But nobody has ever come back. Some people think it is because it is so good there that nobody wants to come back and take the risk of being trapped in the East again. Other think that the people who cross to the West are turned into slaves or even killed. A young boy (I think he is about 12 or so) has no choice : having stolen property from someone he should not have stolen from, his only hope to survive is to go West.
There he finds out the second theory is the correct one. Easterners who reach the West are enslaved and compelled to become (high technology !) gladiators for the pleasure of the Westerners. So they are both slaves and doomed to die eventually.
But the boy, when older, manages to turn the tables. I don't remember any details, except that giving high technology weapons to "gladiators" is not a very bright idea...
