Genre: 2d platformer
Developer: Ideas from the Deep
Publisher: Apogee Software

The legend goes, John Carmack single-handedly invented a way for an IBM XT with a meager 64k EGA card to do full, four-way smooth scrolling-- opening the door, of course, for Super Mario Bros-style platform games! Tom Hall did most of the art work for "Invasion", and in fact aspects such as the overhead lamps from the first episode, or the diagonally-checked backgrounds from the game's second part, are quite evocative! It's a pity that the game uses the stone-standard EGA palette, but even with that caveat Keen is a splendid looking EGA release.

If the graphics are accomplished, then it's par-the-course for the audio, where somehow Carmack and company manage to squeeze memorable, expressive, and redolent sound effects-- for activities such as laser blasts, falling, or the gaining of extra lives-- out of the usually rather grating PC speaker. Like many DOS games of this era, there is no music, but in a way this aural vacuum pronounces the game's atmosphere even more than if there were!

"Invasion" opens with a chapter devoted to wide open "collectathon"-style levels, with excellently spaced and rhythmic platform aspects. The second episode is more puzzle like, emphasizing the use of the game's excellent pogo stick mechanic, along with the introduction of enemies that double as vertical platforms up wall surfaces! Unfortunately, the level design goes into a bit of a tail spin with the third episode's deluge of enemies at every turn-- but even then, the game's nuanced player movements are highly playable.

"Invasion"-- and the fact that it was a technical feat-- illustrates just how far behind the PC was; games on competing platforms, such as the Amiga or the Sharp X68000 in Japan, had titles far more impressive than Keen, multiple years prior! And yet, what started as a Super Mario Bros. 3 clone rapidly morphed into something distinctly different and unique, especially for the aforementioned PC owners, who hadn't yet been able to experience a pure platforming experience such as this, on their computer of choice.