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What is Agentic Coding? (And Why It Changes Everything)

by MrPhil
ai-assisted-developmentagentic-codinggame-developmentclaude-md

What is Agentic Coding? (And Why It Changes Everything)

Two years ago, AI coding meant autocomplete on steroids. You'd type a function name and Copilot would guess the next few lines. Useful? Sure. Revolutionary? Not really.

That era is over.

In 2026, AI doesn't just complete your code — it writes entire features, reads your codebase, makes architectural decisions, runs tests, and fixes its own mistakes. This is agentic coding, and if you're still thinking of AI as a fancy autocomplete, you're already behind.

So What Is It, Exactly?

Agentic coding is a development approach where AI agents autonomously handle coding tasks — planning, executing, and iterating with minimal human intervention.

The key word is agent. Unlike traditional AI assistants that respond to a single prompt with a single suggestion, an agentic coder:

  • Reads your entire codebase to understand context
  • Plans multi-step solutions before writing a single line
  • Executes the plan — creating files, editing code, running commands
  • Tests its own work and fixes errors
  • Iterates until the task is actually done

Think of it less like pair programming and more like delegating to a junior developer who never sleeps, never complains, and gets faster every month.

How It Actually Works

Here's a real example from my workflow. I'm building Stellar Throne, a 4X strategy game, using Claude Code as my primary agentic coding tool.

When I need a new feature — say, a diplomatic reputation system — I don't write the code myself. I write a prompt:

"Add a diplomatic reputation system. Each empire should track reputation with every other empire, ranging from -100 to 100. Reputation should affect trade deals, alliance willingness, and war declarations. Add it to the existing diplomacy module."

Then I walk away and make coffee.

Claude Code reads my entire game codebase, understands my existing diplomacy module, plans the implementation, writes the code across multiple files, and runs my tests. When I come back, there's a working feature waiting for review.

That's agentic coding.

Agentic vs. Vibe Coding — What's the Difference?

You might have heard the term "vibe coding" — writing software by describing what you want in natural language and letting AI figure it out. Agentic coding and vibe coding overlap, but they're not the same thing.

Vibe coding is about the input method — you describe intent instead of writing syntax. Anyone can do it, even non-programmers.

Agentic coding is about the agent's autonomy — the AI doesn't just translate your words into code, it plans, executes, debugs, and iterates independently. It requires some technical understanding to steer effectively.

Vibe coding is how you talk to the agent. Agentic coding is what the agent does after you stop talking.

If you're interested in vibe coding for game development specifically, check out Agentic Game Devs — a community I started for people making games with AI, including non-coders.

The Tools

The agentic coding landscape in 2026 looks like this:

The Big Three:

  • Claude Code (Anthropic) — My daily driver. Terminal-based, incredibly capable at understanding large codebases. Best at autonomous multi-file edits.
  • GitHub Copilot Agent Mode — Integrated into VS Code and now GitHub's web interface. Good for developers already in the GitHub ecosystem.
  • Cursor — IDE with deep AI integration. Composer mode handles multi-file agentic tasks.

New Entrants:

  • Xcode 26.3 — Apple just added agentic coding support, powered by Claude and GPT. Big deal for iOS/Mac developers.
  • Codex CLI (OpenAI) — OpenAI's answer to Claude Code. Just launched GPT-5.3-Codex-Spark running on Cerebras chips at 1,000 tokens/sec.

The Secret Weapon: CLAUDE.md

Most agentic coding tools support project-level instruction files. Claude Code uses CLAUDE.md — a markdown file in your repo root that tells the agent about your project's architecture, conventions, and rules.

This is where agentic coding gets powerful. A well-crafted CLAUDE.md means the agent makes decisions aligned with your vision instead of generic best practices. It's like onboarding a new developer, except you only do it once.

Why Game Devs Should Care

I'm a game developer. I build strategy games and tools. Here's why agentic coding has been transformative for my work:

1. Solo devs can build AAA-scope systems. I'm one person building a 4X strategy game with diplomacy, combat, economy, exploration, and AI opponents. That used to require a team. With agentic coding, I can implement complex systems in hours instead of weeks.

2. Iteration speed is insane. Don't like the combat balance? Describe what you want changed, let the agent refactor it, test it, done. What used to be a "maybe next sprint" conversation becomes a 20-minute task.

3. You focus on design, not syntax. Game development is fundamentally about design — systems, balance, player experience. Agentic coding lets you stay at that level instead of getting lost in implementation details.

4. Non-coders can participate. This is the biggest one. With Agentic Game Devs, I'm seeing people with zero programming experience build playable games using AI agents. The barrier to entry has collapsed.

The Catch

It's not magic. You still need to:

  • Review everything. Agents make mistakes. Sometimes subtle, sometimes spectacular. You are the architect — the agent is the builder.
  • Understand architecture. You can't delegate what you can't evaluate. Knowing how software should be structured matters more than ever.
  • Write good prompts. Garbage in, garbage out. The better you describe what you want (and what you don't want), the better the output.
  • Manage context. Agents work within context windows. Large codebases need strategies — CLAUDE.md files, modular architecture, clear separation of concerns.

Agentic coding doesn't replace developers. It replaces typing. The thinking, designing, and decision-making is still all you.

Where This Is Going

Apple adding agentic coding to Xcode this week is a signal. This isn't a niche workflow for early adopters anymore — it's becoming the default way software gets built.

A GDC 2026 survey found that a third of game developers are already using AI in their workflow. Half of them have concerns about it. I get it — change is uncomfortable.

But here's what I know after building multiple projects this way: I ship faster, I ship better, and I actually enjoy the process more. I spend my time on the interesting problems — game design, player experience, creative decisions — while the agent handles the implementation grind.

That's not a threat to developers. That's a superpower.

Get Started

If you want to try agentic coding:

  1. Pick a tool. Claude Code is my recommendation. Terminal-based, powerful, honest about its limitations.
  2. Start small. Don't hand it your entire codebase on day one. Start with isolated features or utility functions.
  3. Write a CLAUDE.md. Even a basic one makes a huge difference. I'll write a detailed guide on this soon.
  4. Join a community. Agentic Game Devs if you're into game dev. There are also great communities on Discord and Reddit for general agentic coding.

The future of coding isn't writing code. It's directing agents that write code for you.

Welcome to 2026.

I'm MrPhil — I build games and tools with AI, and show you how. Follow along on the devlog or subscribe to the newsletter.