Reduced dynamic budget at low player count (#28300)

* Reduced dynamic budget at low player count

* Tests

* One linty boy

* I was, uh, making sure the test worked. That definitely wasn't a typo. <.<

code/game/gamemodes/dynamic/dynamic.dm

@@ -3,7 +3,7 @@ GLOBAL_LIST_EMPTY(dynamic_forced_rulesets)
 /datum/game_mode/dynamic
 	name = "Dynamic"
 	config_tag = "dynamic"
-	required_players = 10
+	required_players = 0
 	/// Non-implied rulesets in play
 	var/list/datum/ruleset/rulesets = list()
 	/// Implied rulesets that are in play
@@ -26,9 +26,27 @@ GLOBAL_LIST_EMPTY(dynamic_forced_rulesets)
 			possible_rulesets |= ruleset.implied_ruleset_type.name
 	to_chat(world, "<b>Possible Rulesets:</b> [english_list(possible_rulesets)]")
 
+/// Calculates the dynamic budget based on the number of players in the round
+/datum/game_mode/dynamic/proc/calculate_budget(players)
+	switch(players)
+		if(0 to 4)
+			// Flat budget of 7
+			return 7
+		if(5 to 20)
+			// +0.5 budget each for players 5-20
+			// Cumulative total at 20 players: 15
+			return 7 + 0.5 * (players - 4)
+		if(21 to 30)
+			// +1.5 budget each for players 21 to 30
+			// Cumulative total at 30 players: 30
+			return 15 + 1.5 * (players - 20)
+		else
+			// +1 budget each for players 31+, so just player count.
+			return players
+
 /datum/game_mode/dynamic/proc/allocate_ruleset_budget()
 	var/ruleset_budget = text2num(GLOB.dynamic_forced_rulesets["budget"] || pickweight(list("0" = 3, "1" = 8, "2" = 12, "3" = 3)))
-	antag_budget = num_players()
+	antag_budget = calculate_budget(num_players())
 	log_dynamic("Allocated gamemode budget: [ruleset_budget]")
 	var/list/possible_rulesets = list()
 	for(var/datum/ruleset/ruleset as anything in subtypesof(/datum/ruleset))