[{"_id":"1","game":1},{"_id":"2","game":1},{"_id":"3","game":2},{"_id":"4","game":1},{"_id":"5","game":2}]

db.collection.aggregate([{$group:{_id:null,footballCount:{$sum:{"$cond":{"if":{$eq:["$game",1]},"then":1,"else":0}}},basketballCount:{$sum:{"$cond":{"if":{$eq:["$game",2]},"then":1,"else":0}}}}}])