Very rare amount of new people download Starcraft 2 to play Arcade games. They probably don't even know that they exist.
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Pure CTF could work as browser based 2v2, 4v4 and Battle Royale. With Small powerups - could make excellent game. Could and probably would rival Curve Fever in popularity
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The Thing -arctic, this game needs no selling. The top 5 greatest video games, yes video games ever created.
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Zealot Hockey. Greatest hockey game ever created, miles ahead of NHL series. Could be made into a browser game easily like popular kiekko.tk. Also superior game to that.
These are just examples. Lots of games with potential as browser games.