There are basically two common paradigms I've seen online games take with regard to communication between opponents. Most Chess and Go sites allow free chat. Most other games either don't allow communication at all or allow only a very small set of predefined messages like "Hello", "Have Fun", "Good Game", etc (Faeria did this).
Prismata uses the emote system, but there are hundreds of them (and not all of them are text - some are funny animations of a unit exploding for example). When I was first introduced to this system, I thought it was stupid. I thought if you're not going to believe that letting players say things besides pleasantries leads inevitably to toxicity then you should just let players chat with opponents like every Chess and Go site out there does. There's already global chat that you have access to in-game, so why encourage players to pollute the global with match-specific talk instead of just giving them a chat?
But after extensive experience playing ranked Prismata and playing ranked Go and Chess, I learned something. Prismata's emote system encourages communication.
When I played Go and Chess online, I noticed that almost nobody ever said much in the in-match chat. Most matches went by either without a word between the players or just some basic pleasantries like Faeria's emotes. But when I played Prismata, people actually used the hundreds of different emotes. And they used them a lot (at least a lot more than in Chess and Go). Players would sometimes have "emote wars" and in fact there was an emote "I challenge you to an emote war" (as well as a convenient "Challenge accepted" that can be used in other situations too).
It was fun to see how much you could communicate with the limited set of emotes by combining them in clever ways and twisting their meaning slightly. For example, a common combination was "In a moment, you'll be saying the following:" -> "Looks like you win this one." There's an emote "That unit needs to be nerfed" and it was fun to say it and imagine your opponent wondering what unit you mean. Sometimes you could cleverly disambiguate by toggling the unit's ability (which your opponent can see) repeatedly before sending the emote, or by pairing it with one of the emotes that shows an animation of a unit firing. There were so many fun things you can say that wouldn't be fun if you said the exact same things in free chat.
Part of the magic is that pre-written emotes take the burden of choosing wording off the players, and thereby the burden of being self-conscious about it. It might also have one of the same principles as memes behind it: communicating something with a limited set of building blocks is funnier than if you can just say whatever.
And one of the best things was how the devs reacted to the community. I got the "I'm not quite sure how I lost" emote added by suggesting something similar with the in-client provide feedback button, and they sometimes added emotes that reference community memes, like "I'm going breachproof instead", which is a reference to the song Arkanishu wrote and performed in tribute to the game.
Emotes were, of course, part of the game's monetization system. Prismata had no pay-to-win, so they made money by selling cosmetic stuff like unit skins and emotes. Yet you could still unlock all the emotes by grinding. I always thought the devs were a lot more generous with that than I would have been.
And the infusions, too. An in-game collectible item could be used to upgrade specific emotes, unlocking customization options. You could change your emotes' text color, background color and background pattern and even make the text animated. There were some really funny combinations you can do.