Operation Gun : How unlock Simondo

[Kaien]

I did all in Operation gun. Kill all boss, unlock all weapons. Except I dont understand how to unlock Simondo.
The game say : For unlock, kill Simondo.
But I dont know where he is and how fight him ...

The wiki say to upgrade the Diver Mines. I did, but I dont have the option to buy him.

I can play this character in the main game. It is just about operation gun I dont understand I can play him and have the achievement.

[Conte Curatori]

Ah, you are talking about the Adventure.
The wiki talks about how to unlock Simondo for the main game not for the Adventure Mode.
To play as Sigimondo in that Mode, you have to find and defeat his doppelganger while playing Adventure

[Kaien]

Ok. Where can I find him ? Just base on luck or something else ?

[Conte Curatori]

In front of the boss room
He spawns at 05:00

[aklab]

same problem, I'm just replaying every level of that adventure over and over in hopes that I bump into him somehow

[Pan the Sylveon]

I think he spawns near one of the stage items. Just In case: don't use mad groove early in the run or you won't know where to look.

[dgresevfan]

I found him right next to where the giant robot skeleton boss shows up, just earlier in the time limit.