Description
The most important part of this update is to add the Pokemon battle minigame. ´
If you are not familiar with Pokemon battles (or if you are), here’s a YouTube video of an example ´
battle: https://www.youtube.com/watch?v=Jpdy9pZyGH4.
Please don’t ask me why this video has over 2.3
million views1
.
I don’t know. Perhaps there are a lot of professors out there having their students write
Pokemon-inspired games? ´
Pokemon battles are characterized by a turn-based interaction between two trainers or between a trainer ´
(the PC) and a wild Pokemon (the ones which appear in the tall grass). Battles with a wild Pok ´ emon end ´
with the capture of the wild Pokemon, with either the wild Pok ´ emon or the trainer fleeing the battle, or with ´
either the wild Pokemon or all of the trainer’s Pok ´ emon getting knocked out.
Trainer battles end when all ´
of one trainer’s Pokemon are knocked out. Trainer battles cannot be fled, and pok ´ emon are not available for ´
capture in trainer battles.
A Pokemon is knocked out when it’s hitpoints fall to zero. A knocked out Pok ´ emon is unavailable for ´
battle until it is revived.
As with other areas of our game, we’ll be simplifying Pokemon game mechanics in implementing bat- ´
tling. The most important simplifications we’ll make are that we won’t be implementing status effects (there
are simply too many of them to make it a reasonable assignment; but, of course, you’re welcome to do it if
you want to) and we won’t implement Pokemon abilities (for the same reason). ´
Each party takes turns in a Pokemon battle, with each taking an action each turn. If a trainer’s chosen ´
action is anything other than a Pokemon move, this receives maximum priority. If both moves in a turn are ´
Pokemon moves, then the Pok ´ emon whose move has the higher priority ( ´ moves.priority) goes first; if
both moves have the same priority, then the Pokemon with the highest speed (level adjusted) goes first, and ´
if that is also equal, then choose one at random.. If a Pokemon is knocked out or captured before using its ´
move, its turn is forfeit.
Pokemon moves can miss. The chance of a Pok ´ emon evading a move is modified by status effects, which ´
we ignore. This simplifies accuracy to be a simple percentage given by moves.accuracy. If rand()
mod 100 < moves.accuracy, the move hits; otherwise it misses.
Once a move hits, damage is given by the following formula:
2×Level
5 + 2
× P ower ×
Attack
Defense
50
+ 2!
× Critical × random × ST AB × T ype
where Level is the level of the attacking Pokemon, ´ P ower is the power of the move (moves.power);
Attack is the attacking Pokemon’s level-adjusted attack stat; ´ Defense is the defending Pokemon’s level- ´
adjusted defense stat2
; Critical is 1.5 if the attack is a critical hit, otherwise 1; random is a uniformly
distributed random number in [85, 100]; ST AB is the same type attack bonus of 1.5 if the move’s type
matches the attacking Pokemon’s type, else 1; and ´ T ype is the type effectiveness modifier of 0, .25, .5, 1,
2, or 4, depending on both the move type and the target Pokemon’s type (you may use 1 here to simplify ´
1Now 2.5 million views (S2023), 2.7 million (F2023). Want to make bank on YouTube? Post boring af Pokemon videos and ´
monitize that shi-stuff!
2
Pokemon differentiates between ´ attack and special attack (similarly for defense) and physical versus special moves. If you
know nothing about this, ignore this footnote; otherwise, we’re not going to honor these mechanics, so you may handle it however
you like.
The most straightforward solution is to simply ignore special attack and special defense
this mechanic). The move’s damage is decremented from the defending Pokemon’s HP, and the defender is ´
knocked out if its HP reaches zero.
In order to calculate STAB, you’ll need the attacking Pokemon’s type. This is given in ´
pokemon types.type id. You’ll find that many pokemon have two types (are ´ dual typed). A move
gets STAB if any of a Pokemon’s types matches the move’s type. ´
An attack earns a critical hit if it hits and a random number in the range [0, 255] is less than a threshold
value given by b
BaseSpeed
2
c (floor is just integer division!) where BaseSpeed is the base value (not leveladjusted) of the attacking Pokemon’s speed stat. ´
During battle, the PC has the following options, which should all be implemented in the battle placeholder(s) that were added last week:
1. Fight – The active Pokemon uses one of its moves; player chooses the move if PC, otherwise the AI ´
chooses (see below).
2. Bag – Use an item from the trainer’s inventory. We will implement revives, potions, and Pokeballs ´
(more below)
3. Run – Attempt to flee the battle
4. Pokemon – Switch to a different active Pok ´ emon. A trainer may have up to 6 active Pok ´ emon. ´
The fight mechanic is described above.
The bag mechanic consumes an item from the trainer’s inventory. The trainer must be carrying the item
in order to use it. A revive will revive a knocked-out Pokemon and restore it to half its max HP. A potion ´
will restore up to 20 HP, never taking the Pokemon above its max HP value. Pok ´ eballs may only be used in ´
battles with wild Pokemon and will attempt to capture them. ´
The PC may only run from wild Pokemon (battles with trainers must go until all of one trainer’s ´
Pokemon are knocked out). Attempts to run may fail. You may simplify the flee mechanic by simply ´
hard-coding a fixed probability of fleeing.3
Only one Pokemon may be active in a battle at any time. Switching Pok ´ emon will change the active ´
Pokemon. A Pok ´ emon may only be switched in if it is not knocked out. A trainer may carry up to 6 Pok ´ emon ´
at a time. The first Pokemon (e.g., in the array) always starts the Pok ´ emon battle, and switching Pok ´ emon ´
uses the turn.
Start the PC with a small number of potions, revives, and Pokeballs. These items are usable in battle ´
(Pokeballs are only available in battles with wild Pok ´ emon). Detailed catch mechanics can be implemented ´
in 1.10, if you desire. For now, if the PC has fewer than 6 Pokemon, every attempt to catch succeeds, but if ´
the PC has 6 Pokemon, every attempt to catch will cause the wild Pok ´ emon to escape from the Pok ´ eball and ´
flee.
The NPC side of Pokemon battles needs to be “AI” driven. I put this in quotes because you may make ´
your AI as simple or as complicated as you like. It would be sufficient to choose a random move from the
first Pokemon, switching Pok ´ emon only when the current Pok ´ emon is knocked out. ´
3
If you’re interested, the full escape probability is calculated by
OddsEscape =
$
SpeedT rainer × 32
b
SpeedW ild
4
cmod256%
+ 30 × Attempts
where SpeedT rainer is the level-adjusted speed to the trainer’s active Pokemon; ´ SpeedW ild is the level-adjusted speed to the wild
Pokemon; and ´ Attempts is the number of times the trainer has attempted to escape this battle (including the current attempt).
OddsEscape is out of 256, thus if rand() mod 256 < OddsEscape, the trainer escapes.
Pokemon are not restored to full health automatically after battle. Visiting a Pok ´ emon Center should ´
restore and fully heal all of the PC’s pokemon. Visiting a Pok ´ eMart should restore the PC’s supplies (im- ´
plement a shopping mechanic if you would like, but all you need to do is restore the PC’s supplies to the
default numbers they started with). Implement the ’B’ command that will allow the PC to access the bag
outside of battle and apply restores and heals to party pokemon. ´
