This Seeking Tech guide will show you how to get the Running and Gunning trophy/achievement in Metal Slug XX.
You can find the requirements below:
“Clear the game within 45 minutes. Must play through all stages without quitting game.”
To make things easier, make sure you set the difficulty to Easy. You may want to also use Marco, since he can deal twice the amount of damage when using firearms. Afterwards, go through the stages as fast as you can. As long as you play aggressively, you should have plenty of time to spare.
You can check out a video guide for this trophy below: