.

You can click on entries and see who actually entered... you'll only see names currently on the first page (less than 200 or so entries). The other ~5000 pages are empty. Common occurrence. Some shit just overflow. Nothing to see, move along.

Must be a veeery good game :P

Overflow baddy bad ass guys

I've seen this before and I think it happens quite often with this game in particular.

Welcome to Steamgifts !

How can 4 billion people enter it when there're only 7 million people in the world?

Nothing is impossible.
Not even Impossible MIssion for NES!

integer limit

It happens when Gaben joins a giveaway. He's so fat that SG detects him as 4,294,966,000 entries.

Well, the guy who just won that GA is a lucky bastard...

Here's your answer: unsigned integer and integer overflow