Sales are only ‘slightly less.’
Techland’s awesome first person zombie action/parkour game, Dying Light, has now hit 4.5 million unique users, the company confirmed in an interview with Eurogamer. In a refreshing show of honesty, they also came clean and drew a distinction between unique users and cumulative sales, noting that the latter might be slightly lesser than the number of unique users.
“Sales [we] count later – we need time to calculate the sales and returns and so on. Unique users means all the unique users we calculated on the server playing the game for significant number of time. Sales might be slightly less because that includes also secondary sales.”
So yes, if you’ve sold your copy of the game further, or you and your brother are playing it from different profiles, those all count as unique users, but still only one sale for Techland. Keep this distinction in mind.
Still, it sounds that, by all accounts, the game has been very successful for the company, and it also sounds like it was well deserved success, too. Hopefully they can continue on delivering awesome new content.