Alone on Mars

Alone on Mars is a 2D survival shooter on Mars.
An SOS signal was sent from Mars, which was captured by your spacecraft.
You decide to change your course and travel to the planet to figure out what happened.
Upon arrival, you notice that each space station is home to incomprehensible
creatures that appear to have attacked the expeditionary groups and they were
forced to send this signal. Did any of them survive? Are there any traces
their presence? What does the expeditionary program to visit Mars hide?

The gameplay is a platformer with a mixture of sandbox and Tower Defense.
Defend the generator, unlock new weapons and solve the riddle of Mars.