if you DO find something interesting in picking up the project, they'll probably immediately turn around and as you to better spec the project. right now you don't (appear to) have a "spec" - you have an "idea" - and there are many unknowns, just a few as "for examples":
"downloads an image" - is server-side image named literally per the 6 digit code? otherwise, how filename looked up?
"based on the 6 digit code" - if not all 1M images exist, what to do in response to error?
"digit" - as in numberic-only digits, or did you mean chars - 1M numbers or vastly more #charset^6 strings?
"a file" - which? of what type? mysql? text? etc
"on the server" - whose, what capabilities, etc
"is updated" - in what way, using what back-end? php? etc
"stored on the users device" - with original filename? meaning you need to store that filename client-side too. or a single "standardized" name client-side regardless of server-side name?
"used in the game" - again, what happens in case of error? (no network, bad code entered, download failed, etc)
"number of people" - just an incremental count of uniquely used codes, or per "person" tracking, later being able to sum by code to derive counts (if so, what unique id to be used for person) (your requirement of date, below, suggests per-person records and not just "count how many times code was used" - that'd be a derived value, group-by-code query)
"date it happened" - presumably to be server date? (or passed-in client-side date?) any time-zone concerns?
"keep track" - does this imply dev of a back-end "reporting" system too, or you'd do the querying manually? (fe: select code, count(*) from CodeUsageHistory group by code)
i can't take the project, but those are a sampling of the sort of things i'd want to know that you had at least considered before i'd even consider it, and i suspect other devs would be similar, so you might get more bids/responses if you spec'd it out a bit more. hth