Create layers over time
A classic mistake to make when setting up game encounters is to allow all of the AI to attack at once without any spawn delays. The player will end up just being overrun by AI from all directions and the encounter will quickly descends into chaos. There is a good chance that most players discovering this 'surprise' will not enjoy it.
The trick to any encounters is pacing, to stagger the spawning over time and create different waves that are triggered via an event. As the different waves are spawned in, the encounter can eventually build up to a crescendo event and a distinct pause. The break in the flow might seem counter intuitive, but this is the moment to look around, investigate and explore the environment.
Limit attack direction
Most players approaching an encounter will expect the enemies to be attacking them from one direction and will not expect attacks from multiple angles (side or flank) all at once. This does not mean multiple attack directions should never be used, but wide angle (135+ degrees) attacks should either be linked to a skill level or that the player has plenty of good equipment to cope with the situation.
Often players will claim they want enemies to be smart and more intelligent/aggressive with their attacks, but there is a point at which enemy attacks from too many different angles at once can be regarded as cheating or a cheap trick by the level designer. If you are planning to attack the player from multiple angles be aware that this kind of tactic can become tiresome if used too often.
Compliment attack types
Most game enemies have a couple (1-2) of different types (range, melee, AoE or debuff) of attacks and the level designer is responsible for creating different combinations of the enemies with complimentary attacks to challenge the player in different environments. Each enemy individually should not be much of a threat, but once they are grouped together they should become part of a complex puzzle of different threats which the player has to learn how to prioritize in order to survive.
Some group encounters are more difficult than others and that is mainly to do with how many of their abilities overlap and how diverse they are with attack types. A group of enemies which has a single attack (1 melee or 1 range) will be far easier to deal with than a group with a large variety of different attacks because of priority concerns. This is how difficult can be scaled up or down when creating encounters for the beginning or the end of a map.
Roller coaster pacing
Many games are built with a pacing, a distinct ebb and flow to how events unfold and an intensity to the encounters. Some games vary the rate of pacing by using different activities like using reflexes for encounters and lateral thinking for puzzles.
When designing a map try to break it down into zones or bubbles of player activity. Consider each zone being a mixture of different types of encounters and try to vary the pace by having sections where there are puzzles. Remember to keep the combat away from the boundaries to each zone and don't be afraid to create empty spaces to allow players time to breath before the next climb upwards on the roller coaster.
As encounters become more complex with larger groups, multiple waves, and special events, the testing of the pacing can quickly get time consuming because the order of each new encounter will affect the overall flow. I highly recommend to start the testing at the beginning each time to make sure the encounters are balanced in sequence, otherwise there is a good chance a gameplay difficulty spike will appear due to lack of resources.
*Note: This article is published in accordance with Creative Commons Guidelines
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