Here is a video guide on how to go through the full game walkthrough and achievements.
Moncage Walkthrough & Achievements
00:45 – Photo (1/28)
00:55 – Photo (2/28)
01:23 – Photo (3/28)
01:36 – Photo (4/28)
01:49 – Photo (5/28)
02:43 – Photo (6/28)
02:54 – Achievement Quick Reaction
04:13 – Photo (7/28)
05:38 – Photo (8/28)
05:56 – Photo (9/28)
06:13 – Achievement Searchlight
07:44 – Photo (10/28)
08:45 – Achievement Disorientation
09:47 – Achievement Sin
10:09 – Photo (11/28)
10:56 – Photo (12/28)
11:44 – Photo (13/28)
12:14 – Photo (14/28) + Achievement Piecing Together
13:45 – Achievement Sharpshooter
15:15 – Photo (15/28)
15:40 – Photo (16/28)
16:43 – Photo (17/28)
16:50 – Achievement No Mercy
17:48 – Photo (18/28)
18:14 – Achievement Exhaustive Method
19:04 – Photo (19/28)
20:03 – Achievement Shower
20:37 – Photo (20/28)
21:37 – Achievement Time Flies
22:29 – Photo (21/28)
23:22 – Photo (22/28)
24:01 – Photo (23/28)
24:34 – Photo (24/28)
25:29 – Photo (25/28)
26:12 – Achievement Redemption
26:40 – Photo (26/28)
26:53 – Photo (27/28)
27:17 – Photo (28/28)
28:53 – Achievement Subconscious
28:54 – Achievement Wandering Soul
28:55 – Achievement Veteran
29:26 – Achievement Retire in Peace
Thanks to Carrot Helper for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.