The Game Tinkerer – King of Tokyo AI Opponents

The Game Tinkerer – Because no game is ever finished

This is the first in a series of articles I have been meaning to write about modifying games. Be it video games or board games, sometimes the base game is just not enough. It could be a good game I want more of, or a bad game that needs fixing, or just using the constraints of the game to stretch it as far as it will go. I hope to make a few of these articles, covering topics such as house rules, alternate ways to play, video game challenge runs and maybe some game mods.

House Rules – King of Tokyo AI opponents

Today I will be outlining the AI rules I use in King of Tokyo when I want more people to play against. Great if you want a solo variant or just more monsters to fight against.

Hamsters don't make good opponents, they can't sit still long enough

Hamsters don’t make good opponents, they can’t sit still long enough

I have had King of Tokyo for some time now but have struggled to get it out to play with more than three people. Trouble is, as great as this game is, it get better the more people you have. Sure you can pull it out for a party or a gaming meet up but the rest of the week if you live alone or with your partner (like me), it is gonna stay on the shelf. So I developed a way to play against automated opponents. With some simple rules you can have games against some fairly competitive AI players. I have used these rules to play solo and with my girlfriend in three and four player matches and had a good time.

As deep as King of Tokyo is, essentially you only have a few decisions to make; which dice to keep and which to re-roll, whether or not to buy that card you can afford, and whether or not to yield Tokyo when attacked. My rules randomly determine each of these decisions in a way that feels like playing a human opponent, a slightly dumb, very aggressive human, but any more complex and it would be a pain to implement.

AI rules

Rolling and Re-Rolling the Dice

The dice are, despite the re-rolling mechanic, a very random element of this game, so the following rule set will usually simulate a convincing imitation of a human players dice choices.

Each of the three rolls work in much the same way. Rolling the dice, determining the “useless” dice for re-rolling and keeping the good dice. I class the dice faces are numbers and symbols (heart, energy or attack)

“Useless” dice are defined:

  • Any symbols that cannot be used, for example an AI monster will discard hearts if it has full health or cannot attack or collect energy.
  • Any numbers that are impossible to get three of a kind with. e.g. There are two threes but the other dice are already being kept for another purpose.
  • Any single number not repeated (the AI monster doesn’t take risks)
  • Any pair of numbers of lower value than another pair.
  • Attack symbols when the monster is below 4 health and outside of Tokyo

Using this method the AI will generally collect energy, attack monsters, heal when necessary, play less aggressively when near death and try for victory points when a pair or triple is number is rolled.

Buying Cards

Check the number of energy cubes the AI has, if it is enough to buy a card, roll a dice to decide whether or not to purchase it.

If the monster can only afford one card, role a dice, if it lands on an energy or attack symbol buy that card. If more than one card can be bought, do the following:

  1. Role a dice until you get a number, going from left to right (or top to bootom, however you have your three cards arranged) the number on the dice is the starting card.
  2. If the monster can afford the card, roll a dice the same as rolling to buy a single card, otherwise, skip to the next card.
  3. Carry on in this fashion until all cards are bought or skipped, if a new card comes out which the monster can buy, roll for it at the end.
  4. If the monster can afford all three but buys none, it is considdered that it does not want any, in that case, providing it has 5 energy or more, pay 2 energy to scrap cards and draw new ones. Roll to buy any new cards as normal.

Yielding Tokyo

AI monsters will yield Tokyo or not according to their health

8 or more Do not Yield Tokyo.

7 – 5 Roll one dice, if it is a symbol, yield Tokyo.

4 Roll one dice, only stay in Tokyo if it is an attack.

3 or less Yield Tokyo

Using Cards

Some cards can be used at times of the players choice, so assume that the AI monster bought the card to use it. The AI should choose to use card abilities at any point that benefits them, messed with someone else, and won’t hinder themselves.

Golden Rule

The AI will do anything that a human trying to win the game would obviously do.

For example, I played a game where all monsters had 3 or less health, and the AI monsters kept trying to buy a card that would deal 3 damage to all monsters thus ending the game without a winner. I didn’t allow it, sure there would be some sadistic player who might find it fun to screw the game like this but it is not something I would encourage.

Also the AI are trying to win, so if there is a card they can afford that would win the game for them, they should buy it at the first opportunity without rolling the dice. It’s not fun to have to make yourself lose like this, in fact I have made the AI ignore the cards in situations like these and gone on to won, but I know deep down that I lost, I just wanted to play a little more.

So there it is. Give it a go. Feel free to comment if you enjoyed the rules or had any suggestions to make the rules better.


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