Project 14: Steam Cloud Save Sync

Cloud save sync with conflict resolution UX and deterministic merge policy for profile data.

Quick Reference

Attribute Value
Difficulty Level 3
Time Estimate 1 week
Main Programming Language C# (.NET 8) + MonoGame
Alternative Programming Languages F#, C++ (raylib), Godot C#
Coolness Level Level 3
Business Potential Level 3
Prerequisites Deterministic loop basics, debugging discipline, content pipeline fundamentals
Key Topics Sync boundaries, Conflict resolution, Offline first guarantees

1. Learning Objectives

  1. Translate one concrete production question into a testable implementation plan.
  2. Implement and validate the feature in a MonoGame runtime context.
  3. Instrument success and failure paths with actionable diagnostics.
  4. Produce a repeatable demo artifact for portfolio or interview use.

2. All Theory Needed (Per-Concept Breakdown)

Sync boundaries

Fundamentals Sync boundaries is central to this project because it defines the non-negotiable behavioral contract for the feature. You should be able to describe valid inputs, legal state transitions, and expected outputs under normal and failure conditions.

Deep Dive into the concept Treat Sync boundaries as a boundary-setting mechanism. Start by defining the smallest deterministic scenario that proves the feature works. Stress that scenario under altered timing, altered content inputs, and altered user actions. If behavior changes unexpectedly, document hidden coupling and sequence assumptions. Keep transitions explicit and observable via logs or debug panels. Connect each transition to an event record so regression analysis is possible after refactors.

Conflict resolution

Fundamentals Conflict resolution ensures the project scales from local prototype behavior to repeatable system behavior.

Deep Dive into the concept Use Conflict resolution to reason about data flow ownership and mutation timing. Document where writes occur, when validation runs, and how rollback behaves if a write fails.

Offline first guarantees

Fundamentals Offline first guarantees connects this project to shipping reality by forcing you to think about operational constraints early.

Deep Dive into the concept Define one production-like failure mode related to Offline first guarantees and build a mitigation checklist. The solution is complete when you can demonstrate both a golden path and a controlled failure path.

3. Project Specification

3.1 What You Will Build

A Steam Cloud synchronization module with explicit conflict detection, user-facing resolution flow, and backup-safe recovery path.

Visible game deliverable:

  • Cloud sync status panel with local/cloud revision metadata
  • Conflict dialog showing timestamps/playtime/hash
  • Recovery banner after merge or fallback decision

3.2 Functional Requirements

  1. Compare local and cloud revisions before write operations.
  2. Detect and surface conflicts with rich metadata.
  3. Allow deterministic local/cloud resolution with backup creation.
  4. Verify post-sync integrity and display result to user.

3.3 Non-Functional Requirements

  • Performance: Must remain inside project-appropriate frame budget.
  • Reliability: Must recover from at least one injected failure mode.
  • Usability: Outcome must be observable by a reviewer in under two minutes.

3.4 Example Usage / Output

[CLOUD] local_rev=18 cloud_rev=20 conflict=true
[CLOUD] decision=cloud backup_created=true
[CLOUD] verify_hash_match=true PASS

3.5 Data Formats / Schemas / Protocols

  • Event record: {timestamp, module, action, result}
  • Feature state snapshot: {version, state, counters, flags}

3.6 Edge Cases

  • Clock skew between devices.
  • Large save payload near cloud quota.
  • Sync interruption after conflict decision.

3.7 Real World Outcome

This is a game-facing outcome you can see and play immediately.

What you will see in the game window:

  • Cloud sync status panel with local/cloud revision metadata
  • Conflict dialog showing timestamps/playtime/hash
  • Recovery banner after merge or fallback decision

Project 14 Steam Cloud Save Sync Window Mockup

How you interact:

  • S triggers sync
  • C creates synthetic conflict
  • L chooses local; K chooses cloud

3.7.1 How to Run (Copy/Paste)

$ dotnet restore
$ dotnet build
$ dotnet run --project src/Game -- --scene steam-cloud

3.7.2 Golden Path Demo (Deterministic)

  1. Start the scene and confirm all HUD panels load.
  2. Perform the three core interactions listed above.
  3. Verify the success signal appears without warnings.

3.7.3 If CLI: exact transcript

$ dotnet run --project src/Game -- --scene steam-cloud
[CLOUD] local_rev=18 cloud_rev=20 conflict=true
[CLOUD] decision=cloud backup_created=true
[CLOUD] verify_hash_match=true PASS

3.7.7 If GUI / Desktop

+------------------------------------------------------+
| steam-cloud                                   [F1 HUD] |
|------------------------------------------------------|
| PLAYFIELD: gameplay objects and interactions         |
| HUD: key metrics + status badges                    |
| STATUS: success/failure cues and prompts            |
+------------------------------------------------------+

4. Solution Architecture

4.1 High-Level Design

Local Save Snapshot <-> Cloud Snapshot -> Conflict Detector -> User Resolution -> Verified Sync

Local Save Snapshot <-> Cloud Snapshot -> Conflict Detector -> User Resolution -> Verified Sync

4.2 Key Components

Component Responsibility Key Decisions
CloudRevisionTracker Tracks local/cloud revision metadata Use deterministic revision fields
ConflictResolverUI Collects explicit user decision Never hide data-loss implications
SyncVerifier Validates post-sync payload integrity Hash check before completion

4.4 Algorithm Overview

  1. Validate preconditions.
  2. Apply deterministic transition.
  3. Emit feedback and telemetry.
  4. Persist if required.

5. Implementation Guide

5.3 The Core Question You’re Answering

“How do you protect player progress when devices diverge?”

5.4 Concepts You Must Understand First

  1. Sync boundaries
  2. Conflict resolution
  3. Offline first guarantees

5.5 Questions to Guide Your Design

  1. What metadata is required for trustworthy conflict prompts?
  2. When should merge be disabled and explicit choice required?
  3. How do you verify sync completion without false positives?

5.6 Thinking Exercise

Trace one full success path and one failure path on paper before implementation.

5.7 The Interview Questions They’ll Ask

  1. Why did you pick this architecture boundary?
  2. Which failure mode did you prioritize first and why?
  3. How does your instrumentation accelerate debugging?
  4. How would you scale this feature to a larger game?

5.8 Hints in Layers

  • Hint 1: Stabilize one invariant before feature expansion.
  • Hint 2: Add diagnostics before optimization.
  • Hint 3: Keep platform calls at system boundaries.
  • Hint 4: Re-run deterministic scenario after each refactor.

5.9 Books That Will Help

Topic Book Chapter
Core concept “Release It by Michael Nygard” Relevant concept chapter
Reliability “Release It!” Failure handling chapters
Architecture “Clean Architecture” Boundary and dependency chapters

6. Testing Strategy

  1. Golden path completes and emits success signal.
  2. Injected failure path recovers without crash.
  3. Re-run scenario after restart and confirm consistency.

7. Common Pitfalls & Debugging

  • Hidden initialization order coupling
  • Time-coupled behavior tied to render rate
  • Missing fallback behavior on platform call failure

8. Extensions & Challenges

  • Beginner: add one extra diagnostics panel metric.
  • Intermediate: add replay capture for event flow.
  • Advanced: add automated stress test harness.

9. Real-World Connections

This project mirrors shipping feature-module work in real indie and mid-size game teams.

10. Resources

  • Steamworks official docs
  • MonoGame docs
  • Gemini image generation docs (for asset-related projects)

11. Self-Assessment Checklist

  • I can explain the feature invariant and prove it in a demo.
  • I can trigger and handle one deterministic failure scenario.
  • I can describe tradeoffs and future scaling choices.

12. Submission / Completion Criteria

Minimum Viable Completion:

  • Feature works in deterministic golden path.
  • One controlled failure path is handled gracefully.
  • Core diagnostics are visible and documented.

Full Completion:

  • All minimum criteria plus edge-case coverage and regression checks.

Excellence:

  • Includes polished instrumentation and clear productionization notes.