Tower Defense — C++ vs Unity

| Unity / Unreal Engine
Tower Defense — C++ vs Unity

A Tower Defense game built first in C++ with SFML, then recreated in Unity, comparing different development approaches.

I developed the same Tower Defense game twice: first in C++ with SFML, then in Unity with C#. Each version explores different approaches, highlighting trade-offs in control, performance, modularity, and development speed.

Project Context

The objective was to create a 2D Tower Defense game where players strategically place turrets to defend against waves of enemies. The game includes:

  • Multiple tower types with unique mechanics.
  • Enemy waves with varying behaviors and health.
  • A gold-based economy for building and upgrading towers.
  • Projectile mechanics including homing, area damage, and slowing effects.

The two implementations differ in tools and workflow:

  • C++ with SFML (3–4 weeks): Everything built from scratch, including rendering, UI, object lifecycle, and game logic.
  • Unity with C# (1 week): Leveraging engine features such as prefabs, Scriptable Objects, and built-in UI to recreate the game faster and more polished.

C++ SFML Version

Focused on low-level control and modularity:

  • Game Architecture: Managers for rendering, objects, UI, input, and assets. Object lifecycles handled manually with std::unique_ptr.
  • Data-Driven Design: Stats, properties, waves, and animations stored in JSON.
  • Animation & Events: Frame-based callbacks to sync attacks with animations.
  • Custom UI: HUD fully built with SFML primitives.

Key Advantages

  1. Full Control: Every object and memory allocation explicit.
  2. Performance: No engine overhead.
  3. Flexibility: Freedom to implement mechanics exactly as intended.

Challenges

  • Manual memory management required caution.
  • Slower development due to coding every system.
  • Complex systems demanded careful design.

C++ gameplay image

C++ visual studio code image

Unity C# Version

The Unity version prioritized rapid development and polish:

  • Scriptable Objects & Prefabs: Modular data-driven design.
  • Built-in UI: Quick setup of HUD, tower bar, and menus.
  • Improved Visuals: Multiple levels, animations, effects.
  • Reusable Systems: Health, towers, enemies, and attacks designed for easy expansion.

Key Advantages

  1. Fast Development: 1 week vs 3–4 weeks.
  2. Quick Iteration: Drag-and-drop workflow.
  3. Engine Tools: Animation and UI built-in.
  4. Automatic Lifecycle: Garbage collection simplifies memory handling, reducing potential errors.

Unity gameplay image

Unity screenshot

Technical Challenges:

Both versions required a predictive health system to optimize turret behavior:

  • Turrets calculate expected enemy health immediately when firing.
  • Enemies marked as “doomed” by incoming attacks are skipped by subsequent turrets.
  • Dirty flags mark enemies to be removed once damage reaches them visually.

This system ensures no wasted projectiles and efficient targeting. The implementation is conceptually the same in C++ and Unity, though in C++ it required explicit memory and lifecycle handling.

Reflection

Developing the same game twice highlighted the trade-offs of low-level vs engine-driven development:

Feature C++ SFML Unity C#
Development Time 3–4 weeks 1 week
Control Absolute Medium (engine-managed)
Performance High Medium
Memory Management Manual Automatic
Modularity Requires custom design Built-in (SO & Prefabs)
UI & Visuals Fully custom Built-in components

Key Takeaways:

  • C++ gives maximum control and performance, but at higher cost in time and complexity.
  • Unity enables fast prototyping, polish, and modular expansion.
  • Both reinforce principles of game architecture and optimization.