Own CMAKE library

[Spyrex]

Hey, I am relatively new to cpp.
I programmed some classes I want to be able to build to a separate library I can use from another cpp project.

This my directory structure:

Root
- Game/
   - CMakeLists.txt
   - main.cpp
- Engine/
   - CMakeLists.txt
   - src/
      - Engine.h
      - ....
- CMakeLists.txt

Now I want to be able to run a function from Engine.h in main.cpp but I get the error "Velium.h: No such file or directory"


These are my CMakeLists:

Root CMakeLists.txt

cmake_minimum_required(VERSION 3.21)
project(Root)

set(CMAKE_CXX_STANDARD 23)

set(VELIUM_INCLUDE_DIR
        ${CMAKE_CURRENT_SOURCE_DIR}/Engine)

add_subdirectory(Engine)

include_directories(${Engine_INCLUDE_DIR})

add_subdirectory(Game)

ADD_DEPENDENCIES(Game Engine)

Engine CMakeLists.txt

cmake_minimum_required(VERSION 3.21)
project(Engine)

set(CMAKE_CXX_STANDARD 23)

add_library(Engine STATIC
        src/Engine.h)

target_include_directories(Engine PUBLIC lib/imgui/)

target_link_libraries(Engine -lGL -lsfml-network -lsfml-graphics -lsfml-window -lsfml-system -lsfml-audio -lX11)

Game CMakeLists.txt

cmake_minimum_required(VERSION 3.21)
project(Game)

set(CMAKE_CXX_STANDARD 23)

add_executable(Game
        main.cpp)

target_link_libraries(Game Engine)