Multiplayer Game Development

1---
2name: multiplayer
3description: Multiplayer game development principles. Architecture, networking, synchronization.
4allowed-tools: Read, Write, Edit, Glob, Grep, Bash
5---
6 
7# Multiplayer Game Development
8 
9> Networking architecture and synchronization principles.
10 
11---
12 
13## 1. Architecture Selection
14 
15### Decision Tree
16 
17```
18What type of multiplayer?
19│
20├── Competitive / Real-time
21│   └── Dedicated Server (authoritative)
22│
23├── Cooperative / Casual
24│   └── Host-based (one player is server)
25│
26├── Turn-based
27│   └── Client-server (simple)
28│
29└── Massive (MMO)
30    └── Distributed servers
31```
32 
33### Comparison
34 
35| Architecture | Latency | Cost | Security |
36|--------------|---------|------|----------|
37| **Dedicated** | Low | High | Strong |
38| **P2P** | Variable | Low | Weak |
39| **Host-based** | Medium | Low | Medium |
40 
41---
42 
43## 2. Synchronization Principles
44 
45### State vs Input
46 
47| Approach | Sync What | Best For |
48|----------|-----------|----------|
49| **State Sync** | Game state | Simple, few objects |
50| **Input Sync** | Player inputs | Action games |
51| **Hybrid** | Both | Most games |
52 
53### Lag Compensation
54 
55| Technique | Purpose |
56|-----------|---------|
57| **Prediction** | Client predicts server |
58| **Interpolation** | Smooth remote players |
59| **Reconciliation** | Fix mispredictions |
60| **Lag compensation** | Rewind for hit detection |
61 
62---
63 
64## 3. Network Optimization
65 
66### Bandwidth Reduction
67 
68| Technique | Savings |
69|-----------|---------|
70| **Delta compression** | Send only changes |
71| **Quantization** | Reduce precision |
72| **Priority** | Important data first |
73| **Area of interest** | Only nearby entities |
74 
75### Update Rates
76 
77| Type | Rate |
78|------|------|
79| Position | 20-60 Hz |
80| Health | On change |
81| Inventory | On change |
82| Chat | On send |
83 
84---
85 
86## 4. Security Principles
87 
88### Server Authority
89 
90```
91Client: "I hit the enemy"
92Server: Validate → did projectile actually hit?
93         → was player in valid state?
94         → was timing possible?
95```
96 
97### Anti-Cheat
98 
99| Cheat | Prevention |
100|-------|------------|
101| Speed hack | Server validates movement |
102| Aimbot | Server validates sight line |
103| Item dupe | Server owns inventory |
104| Wall hack | Don't send hidden data |
105 
106---
107 
108## 5. Matchmaking
109 
110### Considerations
111 
112| Factor | Impact |
113|--------|--------|
114| **Skill** | Fair matches |
115| **Latency** | Playable connection |
116| **Wait time** | Player patience |
117| **Party size** | Group play |
118 
119---
120 
121## 6. Anti-Patterns
122 
123| ❌ Don't | ✅ Do |
124|----------|-------|
125| Trust the client | Server is authority |
126| Send everything | Send only necessary |
127| Ignore latency | Design for 100-200ms |
128| Sync exact positions | Interpolate/predict |
129 
130---
131 
132> **Remember:** Never trust the client. The server is the source of truth.
133