You may also find it comfortable to use Lazarus, which is an IDE (editor, debugger etc.) built around FPC with a visual classes library (LCL). Our engine components can be used together with Lazarus forms (although we also have an alternative window classes, independent from Lazarus LCL). Currently, we don't have any special requirements on the Lazarus version. Just use Lazarus with a sufficiently up-to-date FPC version.
We also support using NewPascal, a very nice fork of FPC+Lazarus with some new features.
Hint: If you want to install multiple versions of FPC/Lazarus (stable, unstable, NewPascal), with cross-compilers, it is easily possible with fpcupdeluxe.
We do not work yet with Delphi. But we're working on it! Some base units are already compatible with Delphi, you can test it by opening in Delphi and running
examples/delphi/base_tests/base_tests.dpr included in the engine.
We are an official Embarcadero Technology Partner. What this means, in simple terms, is that Michalis has full access to the latest Delphi version, with all the Delphi platforms (including Android and iOS), for free. For testing CGE compatibility.
So, Delphi compatibility is happening. It just takes time. You can support me to make it happen quicker!
As for the Delphi version supported: Right now I focus the port on the latest Delphi, 10.2. But we should be able to support older Delphi versions as well. Any Delphi version that includes support for generics (as we use them heavily) should be OK, which in principle means that we can support Delphi >= 2009.
You can also use Code Typhon, a fork of FPC/Lazarus.
But I (Michalis) advice that you rather use original FPC and Lazarus. I have much more trust in FPC and Lazarus developers doing great quality job, respecting copyrights of other projects (CodeTyphon did some murky things), and working in a transparent fashion (version control, cooperating with other projects).