There are many open source ECS-based game engines written mainly in c++ and rust. 

C++
- crown - General purpose data-driven game engine
- igneous - Open source game engine written in C++
- shiva - Modern Cross-Platform C++ Engine with modularity
- Sparky - Cross-Platform High Performance 2D/3D game engine

Rust
- Amethyst - Data-oriented and data-driven game engine written in Rust
- Bevy - A refreshingly simple data-driven game engine built in Rust

Note that there are different possible implementations of ECS and if you don't find a game engine that suits your needs you can try to make one from scratch.
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence