Soldiers is a good alternative if you are through with Commandos and other RTS games.
To thrive in this game, you'll need to conserve everything, as almost all of the resources are spent per move. Using a tank drains gas. Every missile you fire is gone forever. Every single shell fired from you turret is a unit of ammo. And if you don't care where you go through with the said tank, it will be damaged in the most various of parts. So, if your wheels are damaged, you can't move, same with the turrent and cannon.
The game's graphics are really well made. That's why this game is a huge system hog. It will take some machine to work every little shadow that the game renders and all of the beatiful detailed made from real locations in Germany, Russia and France. The game just feels authentic and real, from the look of the soldiers and their voices, and the music makes even a more dramatic experience.
Control-wise, the game behaves like a RTS. You can bind keys to your keyboard and use them to your will. The mouse will act as a pointer. But there is a catch: you can direct control units with the cursor keys and fire with the mouse. This makes the game even more realistic, since you'll steer that tank avoiding the little plants, that's how precise it is.
Soldiers, like I said above, is a very good game, you'll enjoy its difficulty, it surpasses some really good RTSs in terms of that. I recommend playing Commandos before going through this, as you'll be much more accustomed if you do. If you prefer to jump right in, don't skip the tutorials and don't rip your hair out of your head, arms and legs... :)
Thanks for reading!