Cover Me! Promoting MMO Player Interaction Through Advanced AI

1. Cover Me!Promoting MMO Player InteractionThrough Advanced AI Dave MarkPresident & Lead DesignerIntrinsic Algorithm LLC

2. Dave Mark • President & Lead Designer ofIntrinsic AlgorithmLLC • Game Studio • AI Consulting Company • Author of Behavioral Mathematics for Game AI • Co-founder ofAI Game Programmers Guild • Organizer and co-host of theAI Summit at GDC 2009

3. Premises/Disclaimers • WoW is a good game. • Not everyone wants to be like WoW. • Bad AI has its place in games. • Not everyone wants to have bad AI. • You are here because you are working on an MMO. • You are here because you want to know: • How good AI can make your game better • How to use AI in an MMO environment

4. What makes a game a game? “A game isa series of interesting choices.” - Sid Meier

5. In the beginning… • Early games were entirely played against the computer. • AI sucked • Choices were rudimentary • Problem-solving was simplistic.

6. 1-Player Games w/Multi-player Component • People played against each other more than computer • Game won’t sell without multi-player • 1-player campaign often neglected • “I love Halo 3… but I’ve never played the campaign.”

7. Multiplayer Co-Op • People prefer playing with other people • Interactivity • Teamwork (AI allies still not up to par) • Solving problems together

8. The Draw of PvP • People prefer playing against other people • Difficulty of opponents • Adaptability of opponents • Dynamicity (e.g. the unexpected) • Solving problems together Replayability!

9. The Necessity of PvE • Beyond Game Mechanics • Environments • Weapons • Characters • World Immersion • Who is going to role-play the dragon? • The harmless little bunny? • The slime creature?

10. AI is Your World! Boring AI = Boring World Deep AI = Immersive World Repetitive AI = Monotonous World Dynamic AI = Dynamic World

11. PvP Difficult Adaptable Dynamic Necessitates ongoing problem-solving PvE Simple Rigid Predictable “Solve Once” and repeat PvP vs. PvE PvE • Difficult • Adaptable • Dynamic • Necessitates ongoing problem-solving So how do we do it?

12. Making PvE feel like PvP • Single-player games have been improving their AI to generate a PvP-like feel • What techniques can we import from single-player games into MMOs? • What effect does that have on the player’s individual experience? • What effect does that have on the players working together?

13. By Genre Shooter RPG Strategy By Concept Behavioral Tactical Strategic Simulation Economic AI Techniques

14. By Genre Shooter RPG Strategy By Concept Behavioral Tactical Strategic Simulation Economic AI Techniques Multiple vs. Multiple

15. Behavioral AI • How does the NPC make decisions? • Idle behaviors • When to attack • Who to attack • How to attack

16. When to Attack • Generating “Aggro” • Distance • Environment Threshold Triggers • Line of Sight • Well documented by the public • Attack happens when the player(s) want it to • Removes sense of enemy’s autonomy

17. Who to Attack • Nearest opponent • Strongest opponent • Well documented by the public • Attack is against whom the player(s) expect • Attack is against whom the player(s) want • Removes sense of enemy’s autonomy

18. How to Attack • Primary attack most of the time • After delay of x, use secondary attack • In given situation, use special attack • Well documented by the public • Attack happens how the player(s) expect it to • Removes sense of enemy’s dynamicity

19. Effect on the Players • On the Individual Player • Calculatable • Predictable • Boring • On the Group • No need for interaction • “Read the script…” • “Play your part…”

20. What is your reaction? • Want to pet • Want to meet • Just curious • Annoyed • Want to kick • Want to run screaming

21. Now what is your reaction? • Want to pet • Want to meet • Just curious • Annoyed • Want to kick • Want to run screaming

22. Varieties of Reactions

23. Same Model for All Agents Extreme Reactions

24. Varieties of Reactions • Differences Exist • Don’t need to know why • Need to simulate that difference do exist • Not completely random selection • Must be reasonable • Can be simulated with weighted randoms

25. Know when to walk away… • Design Decision: “Enemies don’t always fight to the death” • Enemies can sometimes retreat • Flat % chance • Is random… therefore looks random • Not realistic • Situational random • Based on circumstances • Circumstances are flexible and dynamic

26. Know when to walk away…

27. Know when to walk away… How many on my side are still fighting? 8 1.6 5 How many of my enemies are still fighting?

28. Know when to walk away… PercentChance = (4 – Ratio)3 / (43)

29. Know when to walk away… PercentChance = (4 – Ratio)4 / (44) PercentChance = (4 – 1.6)4 / (44) PercentChance = 13%

30. Know when to walk away…

31. Know when to walk away… How many on my side are still fighting? 7 1.4 5 How many of my enemies are still fighting?

32. Know when to walk away… PercentChance = (4 – Ratio)4 / (44) PercentChance = (4 – 1.4)4 / (44) PercentChance = 18%

33. Know when to walk away… PercentChance = (4 × Ratio)4 / (44)

34. Know when to walk away…

35. Know when to walk away… PercentChance = ( ( MaxRatio – Ratio )k× MaxPct)/ (MaxRatio k )

36. Know when to walk away… ( ( 4 – Ratio )4 × 1.00 ) / ( 44 ) ( ( 4 – Ratio )6 × 0.75 ) / ( 46 ) ( ( 4 – Ratio )8 × 0.50 ) / ( 48 )

37. Know when to walk away… • Factors to Consider • Number of allies • Number of enemies • Proximity to Base • Strength of allies • Strength of enemies • My own health • Proximity of my leader

38. Know when to walk away… Numberof Allies Strengthof Allies Numberof Enemies Strengthof Enemies Allied Strength Enemy Strength Proximityto Leader My Health Proximityto Base Threat Ratio My Morale “Compartmentalized Confidence” Urgency Retreat %

39. How does this look to the players? • Enemies aren’t completely fearless • They are slightly unpredictable • They are still reasonable • Curiosity: “Where is he going?” • “If we show force, they might break and run.” • “If we back them up, they are more aggressive.” • We have to react to their reactions.

40. More than “Fight or Flight” • Fight normally • Flee • Charge

41. More than “Fight or Flight”

42. Fight Melee weapon Ranged weapon Special rare weapon Advance Press forward Berserker charge Retreat Fighting withdrawal Find Cover Organized pull back Flee in abject terror Surrender More than “Fight or Flight”

43. More than “Fight or Flight”

44. More than “Fight or Flight”

45. More than “Fight or Flight” “Normal” “Defensive” 21% 42%

46. How does this look to the players? • Not predictable • Reasonable • Causes us to have to react to his reaction

47. Target Selection • Who should I attack? • Closest enemy • Biggest threat (highest DPS) • Weakest link (least health) • Most valuable (healer helping the other enemies)

48. Shoot that@$&%#!!

49. Shoot that@$&%#!!

50. Shoot that@$&%#!!