Thus, each player can choose not to repeat the game with other players.
So cheaters can choose to continue to cheat? Doesn't that completely negate the whole point of this system?
It's not just about being able to avoid encountering cheaters, it's also about preventing cheating being possible in the first place. If I can opt out of this system, I can still cheat.
Adding NPC to clash after a timeout.
We already have that, actually. That's the second way to cheat.
Or: doing a promotion.
Yeah, currently my ideas go in a similar direction. Not exactly the same. Promotion can do only so much and it's effect wears off if you repeat it. But I think Clash could be limited to certain timeframes. For example: "You can play Clash in the first 15 minutes of each hour between 5 AM and 10 PM". Something like that. Not sure if that would be "focused" enough, but playing around with the time brackets could do the trick.
Create tv ads
Nope. TV ads are f*ing expensive (both production and airing them) and do not really have an immediate effect of player numbers. They have other purposes (like brand awareness), but for this particular purpose it would be as close as "literally throwing money out of the window" as you can get
And also add RN players for best season (autumn and winter) for online games.
In general we already consider that, whenever we can. Lots of factors go in the decision when exactly we do something, the season being one of them.