Posts Tagged ‘NPC’

Red Faction: Guerrilla

March 21, 2010 Leave a comment

Problem: Conflicts self-escalate and self-perpetuate

Here’s a situation. You’re heading towards an objective, and you pass by one of the EDF Supply Crates that you’re supposed to destroy. You saunter over and take a swing at it with your sledgehammer. A trooper across the street sees you destroying their property, and starts firing. As you take cover, a car pulls up, and several guerillas jump out to ‘assist’ you. They kill the trooper. More troopers show up. They kill more. Pretty soon, the EDF is at red alert, there’s APCs climbing over each other and gunships sniping you from above, and there’s no hope of actually reaching your objective – all because you decided to take a swing at an optional target.

It’s even worse if you start shooting back. The EDF has an unending supply of troops, and as soon as you shoot one of them, they all seem to know where you are. This means that, despite the game’s title, guerrilla tactics don’t work – if you want to ‘hit and run,’ the only place you can run to is your safehouse, a minute or two away…and it’s likely that the EDF will respawn by the time you get back.

It’s not entirely uncommon in open-world games, since destroying cops rightfully tends to attract the attention of more cops. However, Red Faction: Guerrilla has two design choices that aggravate the problem. First, if the area supports you, guerrillas will arrive and fight with you during combat. That’s really cool, except that there’s no way to let the Red Faction know when to knock it off and disengage. Second, there’s no Pay n’ Spray (from the GTA series) or equivalent to allow the player to escape pursuit or lose their alert level. They can retreat to a safehouse, but there are only a handful of those scattered across the entire game world.

Solution 1: Add ‘disengage’ logic to guerrilla AI

With a few tweaks to their AI, the guerrillas can be helpful to an escaping player, rather than dragging them into further conflicts.

First, we need a way to identify when the player is attempting to evade instead of fight. It doesn’t need to be a very complicated system, though. Just keep a hidden numerical variable to track the player’s attitude. Once per second: +1 if the player doesn’t fire a weapon. +1 if they don’t cause any damage. +1 if they’re sprinting. +1 if they don’t take any damage. +3 if no enemy units have line of sight. -3 if the player fires a weapon. -5 if they cause damage. -1 if they take damage. -50 every time the alert level increases. If the number gets to 50 or above, the player is considered to be evading, rather than fighting. If they take actions to lower their number again, their status can change back to fighting.

If the player is evading, their guerrilla allies attempt to help them escape. They stop trying to kill the EDF, and start laying down suppressive fire, moving away from the battlefield, and looking for vehicles to escape in. As they disengage, the EDF assumes they’ve won the conflict, and the alert level drops rapidly.

If the player is evading and on foot, running away from the conflict, they will get a radio message that a prepared vehicle is being sent for them. Shortly thereafter, a vehicle will pull up nearby. If the player takes this vehicle and avoids any illegal behavior for a short while, their alert level will drop. (The vehicle is nondescript, radar-camouflaged, a diplomatic vehicle…any explanation is just as good as another.) This ‘pull-up-and-leave-a-vehicle’ behavior already exists in the game, so the only change that needs to be made is causing the vehicle to affect the player’s alert level.

Solution 2: Create stealth abilities the player can purchase and use

Another way to allow the player to escape is to give them more control over escaping from a conflict.

In Red Faction: Guerrilla, the player has an NPC ally, Samanya, who offers them weapon and item upgrades in exchange for salvage (currency). As an armor upgrade, Sam will offer stealth upgrades to the player’s heavy Martian coat. The player would activate these abilities by holding down the Crouch button (L3 on PS3), and the abilities would last until they draw a weapon or take damage. They can use their stealth as much as they want, although high-tech stealth solutions have a cooldown time before they can be used again. Red Faction: Guerrilla is still an action game, not stealth action, so the player shouldn’t be able to rely on stealth for offense too often.

At the beginning of the game, all the player can do is turn up their collar, hide their weapon, and try to look nonchalant. Even this can be helpful for disappearing into a crowd.

1/4 way through the game, Samanya offers the player a quick-change coat, which can rapidly be turned inside out or otherwise modified to appear as a different style of clothing.

1/2 way through the game, the player can purchase automatic camouflage, similar to Old Snake in Metal Gear Solid 4. If they crouch and move slowly, their coat will automatically change color to match the closest surface. This makes long-range attackers, especially gunships, much less likely to notice and attack the player, and allows the player to attempt evasion even with no civilians nearby.

3/4 way through the game, true invisibility becomes available. The invisibility cloak only lasts for a few seconds and has a recharge time, but it allows the player to move to a different hiding spot, climb in a vehicle unnoticed, or slip past an EDF blockade.

None of these items offer a perfect escape from a conflict, but they all allow a player to have more control over their attempt to escape. They’ll also promote more guerrilla tactics, where a player can strike at the EDF then disappear into the crowd, without being drawn into an extended conflict.


Brütal Legend

March 20, 2010 Leave a comment

Problem: Difficulty curve based on optional exploration

The single-player mode of Brütal Legend features a number of scripted storyline battles, interspersed with periods of activity where the player can roam around the game world, earning upgrades and finding hidden statues to increase their life and power. Hidden solos also give the player new abilities that can turn the tide of battle.

However, the player is not required to explore, and may move on to the next story mission at any time. The game’s difficulty is based on the assumption that the player has explored and earned some upgrades, so moving on too quickly can throw the player in over their head, causing the storyline missions to become difficult and frustrating. This problem is compounded by the story of Brütal Legend – it’s excellent, engaging, and well-written. As a player, I found myself much more interested in advancing the main plotline than spending time improving my character.

Solution: NPCs judge the player’s strength and offer advice

Brütal Legend needs to gate the player somehow, to encourage them not to bite off more than they can chew – but without making the restriction obvious. To do so, we’ll use the strength of the existing storyline, by having the warning come from the NPCs.

When the player talks to an NPC to start a storyline mission, the game checks how many upgrades they’ve found. If they haven’t found enough Bound Serpents, Fire Tributes, or Solos, the NPC will encourage them that they need to scout out the area further.

The player then has a choice: they can attempt the storyline mission, or choose to explore more. If they choose to attempt the mission, the NPC tells them that it’s suicide, but doesn’t otherwise get in their way.

If the player chooses to explore more, the NPC mentions that they saw some kind of relic or power-up that Eddie should go check out. The location is marked on the player’s map, meaning that even the most exploration-challenged player will never be totally stuck in the game. With any luck, the player will also discover a few other power-ups while they’re out in the world.

By having the NPC give this warning, it ties the need for exploration into the main plotline. The NPCs of Brütal Legend are supposed to be experienced warriors, and it makes sense for them to give battle advice to Eddie. If the player has become invested in the storyline and respects their NPC allies, they should be more likely to heed their warnings and strengthen themselves, staying closer to the game’s intended difficulty curve.