DarkBASIC
Enteractive Software, Inc.
I'll admit it - I have never used DarkBASIC. On the other hand, I do know a collection of people who have and who swear by it.
For beginners, DarkBASIC offers an easy scripting language, full support for 3D environments, and a great tutorial, important for those who are just getting started.
Advanced users will quickly get to grips with the language, and begin to create games in a way that has never been so easy and fluid.
You may not create the next Quake or DOOM, but DarkBASIC will certainly allow you to build solid prototypes efficiently; expert programmers may find it a little limiting.
Borland C++ Builder
Borland International
For those who want to build experience with real programming, C++ is the language of choice. So much of the code snippets out there, in books and on the web, are in C++ that it is vital to become fluent.
From a personal point of view, I much prefer building applications with Borland products over Microsoft ones, and not just because they tend to be cheaper, although that is important if you are on a budget.
The IDE is clean and well-documented, their skeleton application structure is slightly less intuitive then MFC, but very powerful once you get used to it.
Borland has taken some of the key Visual Studio concepts, and improved on them to the point that returning to the Microsoft equivalent seems somehow frustrating and cumbersome.
If you are going to program in C++, be it for fun or profit (and even cross-platform), then you cannot go far wrong with C++ Builder.