Unreal Engine is a game engine which uses C++. It might be what you're looking for

Edit: Sorry, didn't see you mention Unreal in your original post.

You might want to look at SFML, although technically it's not an engine (it's more like a framework than an engine) ...

You can't use C++ in Unity.  It supports C#, and used to support UnityScript (similar to JavaScript) and Boo (similar to Python) but has dropped support for both of those.  There are some assets such as "PlayMaker" that can allow you to use visual scripting rather than C# in Unity.

Unreal is probably the main engine option that uses C++ (or a visual scripting system called Blueprints), but you mentioned in your post that you were looking for alternatives.  Can you tell us why you're looking for alternatives?  The answer may help us to recommend alternatives.

You could also consider CryEngine , but it's not commonly recommended; it's a bit of a mess and can be confusing, is not well documented, and you won't find a lot of community support. Amazon Lumberyard may be a better alternative -- it's based on an older version of CryEngine but has had some work done to clean up and modernise the code base, add some new features (many of which are some sort of integration with Amazon's other services), and produce some new documentation.  I haven't heard of a lot of people using Lumberyard as of yet though, so again you may not find much community support.

Godot is written in C++ and is open sourced, as mentioned above.  You could develop a game using C++ with Godot, but it's not technically one of the main supported options (this is supported through the GDNative API - see below); it's intended that you would use GDScript (a custom scripting language, a little similar to Python), C#, or the provided visual scripting system, and to add-on to the engine or optimize scripts using C++.  Godot is relatively new but has an active and growing community, and a growing amount of documentation - if you're doing anything unusual you may be largely left to your own devices though.

You could also consider working with a language that is similar to C++.  Urho3d is written in C++, open source, and the main supported scripting language is AngelScript , which aims to be similar to C and C++.  Lua is also offered as an option, and I believe you could also work in C++.  As a lesser-known engine there is unfortunately less documentation and community support available, although there are a few Urho users here in our community.  It also doesn't officially have a visual editor like Unity/Unreal/Godot at this stage as far as I'm aware, although I'm told there is an experimental editor under development.

You could also work at a lower level using an API such as SDL , SFML , or Allegro (C based, but very usable from C++).

Hope some of that helps!

1 minute ago, gaxio said:

Godot has explicit support for this with the GDNative API.

My understanding was that this was more for adding features or optimizing than for use as your main scripting interface, but it seems I misunderstood, thanks for the correction!