An addon for the original Behind Enemy lines
Commandos: Beyond the Call of Duty is mostly a mission pack for the original Commandos, bringing a much needed set of new maps and missions, for those that had exhausted the (limited!) resources of the original game, it's missions and bonus missions (for those that were able to fulfill all the side missions hidden within each level!). So, beside these missions, which expand the game quantitatively as well as qualitatively (by adding new types of challenges, some that actually require really intricate levels of collaboration) the addon also addressed a few minor interface issues, making switching between characters a little bit easier. In terms of difficulty, yes, the expansion kind of addresses those that have at least played through a few of the original's scenarios. It's not that it is insanely difficult, but it sure doesn't let you get away as easily with sloppy, non tactical play. But, the new puzzles/tactics situations make sense, and, as I said, won't put you in the ropes immediately, though surely you'll need to have paid your dues in the original. Graphically it's the same engine, the same art direction, so not much change there, which is for the better really. This first game in the series was astonishingly well executed, personal and always great for 2D. Definitely play it if you've loved other 2D Commando games.