Obtained the Solar Gun.

Missable.

To get the Solar Gun, you must collect all possible Dolls. These are little prizes you get in the game when you defeat the Beauty and the Beast members non-lethally (for example, defeating them with a tranquiliser) when in their BEAST forms. Its a pretty simple task when you think about it. You must get the Dolls of Laughing Octopus, Raging Raven, Crying Wolf and Screaming Mantis. You must also collect the Haven Trooper/FROGS doll.

• Frog Soldier Doll: Defeat all Haven Troopers non-lethally in the ambush with Meryl and find it in the garage in the Middle East Advent Palace in Act 1 (Middle East).
  
• Laughing Octopus Doll: Defeat her BEAST form non-lethally in Act 2 (South America). The doll can be found on one of the beds. You must pick this up before defeating Laughing Beauty.
  
• Raging Raven Doll: Defeat her BEAST form non-lethally in Act 3 (Eastern Europe). The doll can be found atop the tower. You must pick this up before defeating Raging Beauty.
  
• Crying Wolf Doll: Defeat her BEAST form non-lethally in Act 4 (Shadow Moses Island). The doll can be found by looking behind you when standing at the starting position. You must pick this up before defeating Crying Beauty.
  
• Screaming Mantis Doll: Defeat her BEAST form non-lethally in Act 5 (Outer Haven). The doll can be found just outside the northern door. You must pick this up before defeating Screaming Beauty.
  

In the next playthrough after collecting all five Dolls, youll obtain the Solar Gun when meeting up with the Mark II for the first time.