Conversation so far:
When did Card start writing science fiction?
was eventually purchased by Ben Bova at Analog Science Fiction and Fact and published in the August 1977 issue.
What was the name of the story Analog published in August 1977?
He wrote the short story "Ender's Game" while working at the BYU press.
So, Ender's Game was first published in Analog magazine--when did it become a book?
Ender's Game and its sequel Speaker for the Dead were both awarded the Hugo Award and the Nebula Award.
Who was the publisher of Ender's Game?
CANNOTANSWER.
Was Ender's Game his first published book?
Card continued the series with Xenocide, Children of the Mind, Ender's Shadow, Shadow of the Hegemon, Shadow Puppets, .
How was Ender's Game received by critics?
Ender's Game and its sequel Speaker for the Dead were both awarded the Hugo Award and the Nebula Award.

Question: How large an advance did he receive for Ender's Game?
Self-contained rewrite: How large an advance did Orson Scott Card receive for Ender's Game?