muh immursion

code/controllers/configuration/configuration.dm

@@ -414,3 +414,20 @@
 				continue
 			runnable_modes[M] = probabilities[M.config_tag]
 	return runnable_modes
+
+/datum/controller/configuration/proc/LoadChatFilter()
+	var/list/in_character_filter = list()
+
+	if(!fexists("[directory]/in_character_filter.txt"))
+		return
+	log_config("Loading config file in_character_filter.txt...")
+	for(var/line in world.file2list("[directory]/in_character_filter.txt"))
+		if(!line)
+			continue
+		if(findtextEx(line,"#",1,2))
+			continue
+		in_character_filter += REGEX_QUOTE(line)
+
+	ic_filter_regex = in_character_filter.len ? regex("\\b([jointext(in_character_filter, "|")])\\b", "i") : null
+
+	syncChatRegexes()

code/modules/mob/living/say.dm

@@ -88,11 +88,21 @@ GLOBAL_LIST_INIT(department_radio_keys, list(
 
 	var/static/list/one_character_prefix = list(MODE_HEADSET = TRUE, MODE_ROBOT = TRUE, MODE_WHISPER = TRUE)
 
+	var/ic_blocked = FALSE
+	if(client && !forced && config.ic_filter_regex && findtext(message, config.ic_filter_regex))
+		//The filter doesn't act on the sanitized message, but the raw message.
+		ic_blocked = TRUE
+
 	if(sanitize)
 		message = trim(copytext_char(sanitize(message), 1, MAX_MESSAGE_LEN))
 	if(!message || message == "")
 		return
 
+	if(ic_blocked)
+		//The filter warning message shows the sanitized message though.
+		to_chat(src, "<span class='warning'>That message contained a word prohibited in IC chat! Consider reviewing the server rules.\n<span replaceRegex='show_filtered_ic_chat'>\"[message]\"</span></span>")
+		return
+
 	var/datum/saymode/saymode = SSradio.saymodes[talk_key]
 	var/message_mode = get_message_mode(message)
 	var/original_message = message

config/in_character_filter.txt

@@ -0,0 +1,7 @@
+###############################################################################################
+# Words that will block in character chat messages from sending.                              #
+# Case is not important. Commented-out examples are listed below, just remove the "#".        #
+###############################################################################################
+#lol
+#omg
+#wtf