What game engine was Terraria built with?

Terraria was built in C# on Microsoft's XNA Framework, a set of libraries for making games on Windows and Xbox 360. Re-Logic wrote its own game code on top of XNA instead of using a ready-made engine like Unity or Unreal, so in practice Terraria runs on a custom engine built with XNA.

Why XNA and C#

When Andrew "Redigit" Spinks started Terraria in January 2011, XNA was a popular free choice for independent PC developers. It handled graphics, sound and input, and let a small team write gameplay in C# quickly. Terraria launched on PC in May 2011.

What happened after XNA

Microsoft stopped developing XNA, so later versions of the game moved to compatible open-source reimplementations, such as FNA on macOS and Linux, while keeping the same C# codebase. Console and mobile versions were ported, sometimes by partner studios, using their own technology.

Why it matters for players

• Modding: because the game is written in C#, the community built tModLoader, a free modding tool released on Steam with Re-Logic's support.
• Performance: the tile-based 2D world is handled by Terraria's own code, which is why large worlds and many entities can still slow older PCs.

FAQ

What programming language is Terraria written in?

C#. Mods made with tModLoader are also written in C#.

Who developed Terraria?

Re-Logic, the independent studio founded by Andrew "Redigit" Spinks. Some console and mobile versions were ported by partner studios.

When was Terraria made?

Development started in January 2011, and the game launched on PC in May 2011. Re-Logic kept adding major free updates for more than a decade.

Is Terraria made in Scratch?

No. Terraria is a commercial game written in C#; fan remakes in Scratch exist but are not the real game.