If you look at the docs: Reference | Twitch Developers you’ll see that there is no querystring param called game. That endpoint has 2 params, id, and name and at least one is required.
That isn’t even an endpoint, there is no Top Videos in Helix.
That’s what the Helix Get Games endpoint is for, if you provide it with an id you get given the game which that ID is for. Alternatively you can give it a name. This is a 1 to 1 lookup though, it requires an exact match, there is no ‘search’ in Helix at this time.