The GCS creators claim that their combat system is the fastest growing combat system in Second Life and their region list shows that about 80 regions are offering shooter game experiences based on their system. The GCS approach is different to other Second Life combat systems. GCS does not only provide weapons and a meter that measures the players health. They provide a whole game construction kit for region owners. The GCS system includes - amongst many other items - all kind of monster spawners; exploding cars, barrels and dumpsters; low lag city building kits; scoreboards; recovery systems; fog machines; breakable glas; quest items and even quest NPCs (non playing characters).
The range of NPC adversaries is not limited to zombies. There is also a medieval theme available with elven, orc and goblin spawners or a Sci-Fi theme with alien and robot spawners.
The GCS HUD measures the player's health, holds the inventory, counts the kills and awards with experience points that will level the player up over time. Those points are also counted by a scoreboard that compares the performance of all active players. If the player dies, he/she needs to restart from the beginning: the hud will make a teleport button appear which resets the game.
There are also inventory slots build into the HUD for special objects you may either purchase or be awarded from doing quests that can help your character. "Health potions" will heal your wounded character, "Armor potions" restore your armor and "Effect potions" that may cure disease, or strengthen your defenses. A great GCS features is the GCS Potion Backpack which can be worn on the player's back. When you left click on it you will see a menu and it will give additional space (to the HUD) for collecting potions.
A very interesting feature is the Player versus Player (PVP) modus. It can be enabled or disabled, depending on if you want to fight NPC enemies or other players. When PVP is ON other players will be able to shoot and kill you. Since the GCS is a very sophisticated combat system I think that it holds great potential as a RPG contest tool. I would certainly prefer it to most combat systems in use.
Last but not least the region owners have the opportunity to set-up quests with GCS. Questing can be fun and a great way to gain experience points and sometimes free rewards such as potions, weapons, or other custom goods. Players need to locate a quest giver - usually an NPC (Non Player-Character). Clicking or bumping into the quest NPC begins a dialogue in open chat. It will tell the player what has to be accomplished in order to earn experience points.
One other neat feature that most other combat systems in Second LIfe are missing is the pause button. Pressing it will lock the avatar so the player may not be killed or take any damage. A very helpful feature for any unforseen RL event - now you can run to the bathroom, or change a diaper, or answer the phone without having to start a game from scratch.
The Grim Combat System is the most advanced gaming and combat system that I have come across in Second Life and it has transformed many regions into great game zones. There is only two wishes that I have for the future: Firstly I hope that the monster spawners will get a certain artificial intelligence, so that they spawn monsters only once for a player and stop appearing infinitely. The shooter sim "The Maze" proofs that suc a feature is can be programmed in Second Life. The other odd thing is that one cannot shoot the monsters when they come too close. The player has to gain some distance first and then continue shooting. It would be great if enemies could be shot from any range. But that's only two little suggestions for improvement for an otherwise outstanding combat system.