One possibility is to filter 'games' that have "playtime_forever": 0
.
As an example, this would filter appids 9, 92, 211 from the below snippet.
{
"appid": 9,
"playtime_forever": 0
},
{
"appid": 92,
"playtime_forever": 0
},
{
"appid": 211,
"playtime_forever": 0
},
{
"appid": 440,
"playtime_2weeks": 188,
"playtime_forever": 107307
},
This is going to catch everything for you though, because people that have 'played' these games will have play time. So, for the above you would have filtered out the Source SDK, but for another user that has used it the SDK would appear.