An evolution rather than a revolution, Planet Strike! doesn't dramatically change things and features everything from the original game except the elevator. In the place of the elevator, the player must now collect a bomb on every map and bring it to a security cube; the bomb will destroy the cube allowing the player to use the exit.
It features 24 new levels, played in a single episode in a linear fashion (despite a between level map trying to convince you otherwise), a new weapon, the Plasma Discharger (which functions as the game's ultimate weapon), and several new bad guys and bosses.
Though the "new bad guys" comment is a little misleading as only one of them is actually all new; the others are the boss aliens from Aliens of Gold (with their stats reduced to non-boss level) or simply slightly edited and re-coloured bad guys from the previous game.
Although the developers claimed to have created "all new aliens and guards" for Planet Strike, if you really look closely you can see that the "new" guards are really just the original three guards, recolored a bit to look more alien-like. Similarly, a lot of the "new enemy sounds" in Planet Strike are the same sounds that existed in Blake Stone: Aliens of Gold, just played backwards.
Source Code
On July 9, 2013, Apogee released the source code for Blake Stone: Planet Strike!; almost 19 years after the original release. The source code was long believed to be lost. It can be downloaded from http://www.apogeesoftware.com