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 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.
We also support Code Typhon, a fork of Lazarus.
Although Michalis suggests that you use proper FPC and Lazarus instead. I simply have more trust in FPC and Lazarus developers doing great quality job. Lazarus comes now with Online Package Manager and you can use fpcupdeluxe to easily install cross-compilers — these cover some often-mentioned Code Typhon advantages.
But you are free to use any tool you choose.