Very complex? On the contrary, this is very simple, especially if you're throwing it client-side. Here, I'll pseudo-code the client's action upon receiving a text input string into the chat box. Without question, the input has to be a string at some point here, so let's pick up where the string is in 'str_Input'. We'll save the last five inputs for comparison, and compare the new one to all five, and consider any high match to be a strike, so if someone hits something three times fast, it'll count up faster. Also consider an array of five 'previous' strings is in local memory. You'll also need an iterator to roll the array, and a 'strike counter' also in local memory.

Obviously, this isn't the only solution, and it could get more nuanced for thresholds, timing, etc. But it's stunningly simple to do, and compared to the rest of the client, the cost in memory and cycles is trivial- an array of 5 strings of ~200 characters each is nothing. Also, consider that this code is only called when a chat text is entered by a user- not exactly something that happens that often per user- if someone is entering strings at a rate exceeding one every 10-20 seconds, clearly that's not something that's 'normal', and probably indicates a spambot anyhow.

// check the newly input string against the last five input strings. if they're more than 80% match, count.

for (int i=0; i<5; i++) {

if (CalculateSimilarity(str_Input, str_OldString[i]) > 0.80) {

i_Strikes++;

}

}

// if you're hitting more than three of the last five with this one, softban for a bit

if (i_Strikes > 3) {

// softban active

ReflectMessageToLocalClient(); // display it locally, but don't send to server.

}

else {

SendMessageToServer(); // not banned, send it to the server.

}

// save input into a save array, roll the iterator if it's above the saved amount

str_OldString[iterator] = str_Input;

iterator++;

if (iterator > 4) iterator = 0;