I believe that you are using the wrong API endpoint for this. Use GetUserStatsForGame .
Your call will look like this:
http://api.steampowered.com/ISteamUserStats/GetUserStatsForGame/v0002/?appid=730&key=<<KEY>>&steamid=<<PROFILEID>>
Instead of <<KEY>> you will replace your API key and <<PROFILEID>> with the profile identifier (not SteamID) of the user you are interested in. This value will be the same as you when you log in through Valde OpenID.
This will return a result similar to this:
{ "playerstats": { "steamID": "7656-EDITED-OUT", "gameName": "ValveTestApp260", "stats": [ { "name": "total_kills", "value": 110527 }, { "name": "total_deaths", "value": 95930 }, { "name": "total_time_played", "value": 5784386 }, { "name": "total_planted_bombs", "value": 2726 }, { "name": "total_defused_bombs", "value": 594 }, { "name": "total_wins", "value": 26937 }, ... ] } }
You can see that you need to iterate through the ['playerstats']['stats'] element and look at the name attribute of each to find the statistics you need.
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