Monday, 30 June 2014

An Improved AI For Machinas

Machinas plays very nicely solo, but sometimes the AI doesn't seem very sensible. Well-armed NPC vehicles rarely use their weapons, for example, and the system doesn't cover some of a vehicle's more unusual options.

As I've played games I have been tweaking and adding to the system in order to make the behaviour of NPC vehicles more 'intelligent', which in turn I hope makes them into more challenging opponents.

I have tried to develop a system which will apply to both Races and Road, and will note the differences accordingly. In essence a race will still emphasise passing, and vehicles may be more conservative about expendable weapons until towards the end of the race. On the road, vehicles will be more aggressive, as the aim is to eliminate the opposition within a limited time-frame.

Bonus Dice

A vehicle will always roll to use Bonus Dice on the Bashing, Shooting or Out Of Control Tables.

A vehicle will always roll to use Bonus Dice if it is attempting a Pass.

If a vehicle is being passed, it may opt not to use Bonus Dice. Look at the number of Successes of the passing car and compare it to the number of Auto Successes the NPC car has.

If the number of Passing Successes is less than the number of Auto Successes, then the NPC holds off the Pass without using any Bonus Dice.

If the number of Passing Successes is equal to or greater than the number of Auto Successes, then determine how many dice the passed car would roll without any Bonus Dice, halve the total and add it to the Auto Successes. If this score is greater than the number of Passing Successes, then the passed car will roll to use Bonus Dice, but each will only be used on a roll of '1'.

Otherwise roll for Bonus Dice use normally.

Example: Red attempts to pass Yellow on a straight. Red scores 5 Successes. Yellow has a Speed of 3. This means that Yellow's Auto Successes are lower than Red's Successes (3 vs 5). Yellow's Savvy is 4, and he is on the inside, so he would automatically roll 5 dice. Halved this is 2.5, and added to his speed of 3 this gives 5.5. This is greater than Red's score, so Yellow will roll for each Bonus Dice, using it on a '1'. Had Yellow not been on the inside, his total would have been 5, which would not have been greater than Red's, so Yellow would have rolled for Bonus Dice use normally.

Winning A Pass

If an NPC car wins a wide pass, then it will just pass - there is no other option.

If an NPC car wins a normal passing attempt, then you must determine if it will Pass, Bash or Shoot. This is how we do this.

At the start of the game, assign each NPC car a Primary, a Secondary and a Tertiary behaviour. Each of these must be either Pass, Bash or Shoot, but a behaviour may be used more than once. For example, a car equipped to do nothing but bash may have Bash as its Primary behaviour, Pass as its Secondary and Bash again as its Tertiary.

In a Race all cars will generally have Pass as their Primary behaviour, so a car with Twin 50's may have its behaviours defined as Pass/Shoot/Bash in a Race, but Shoot/Pass/Bash on the Road.

When a car wins a Passing attempt roll a D6:
1-3 - The car uses its Primary behaviour
4-5 - The car uses its Secondary behaviour
6 - The car uses its Tertiary behaviour

If the car was being Passed, and won, then make the roll as normal. Treat results of Pass and Shoot as Holding Off The Pass, unless the car has a Tail Gun in which case both results are treated as Shoot.

Other Behaviours

In a Race, if an NPC vehicle has the option to use something with limited uses, roll a D6. They will use it on a roll of 1-3 on a D6. They will automatically use it if the number of uses remaining is currently greater than or equal to the number of track sections remaining. This applies to such things as Molotov Cocktail, Flamethrower, Box of Nails. On the Road an NPC car will use such expendable items at the first opportunity

If an NPC car has the option to make a special challenge instead of a normal Passing attempt challenge (firing a Tail Gun at a target behind them, or Missiles at a target two or three spots ahead, for example), then they will do so on a roll of 5+ on a D6. 

On the Road, a pursuing NPC car that is is front of all pursued vehicles will declare Dropping Back in the Challenge Phase on a 5+ if their Primary behaviour is Bash or Shoot. If their Primary behaviour is Pass, then they will only Drop Back on a 6.

If an NPC car has the option of changing lane (via a random event, for example), then they will do so on a 5+ of a D6.

When an NPC car has the option of moving into or passing via the inside or outside lane, they will go Inside on a 1-4 and Outside on a 5-6

When rolling for position at the start of the turn, an NPC with Loner will go Out of Position on a 1-2, attempt a Wide Pass on a 3-4, and a Normal Pass on a 5-6.


This may look involved, but in fact it's fairly easy to keep track of during the course of a game, and makes for more sensible NPC vehicles, especially in chases.

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