How the graph works:
With the fourth entry we see a dramatic increase in graph size. We won't see a larger graph appear in the series until submachine 8, so it still stands as one of the largest submachine games.
The Lab opens up with a simple tutorial where you must find a hammer to break open a lock to the attic. The player then opens up a small portion of the lab and is given three of the seven keys for a multi key lock involving making acid. Skutnik then does a troll and shows the player a locked door and hangs a key next to it, but it doesn't fit in the keyhole. What the player must do is take the chimney sweeper and sweep the pipe to find a door key stuck in the chimney. Cheeky.
With the door unlocked the player opens up access to the rest of the lab, apart from the teleporter. The game then reveals just how large it is going to be by giving the player coordinates to six new areas. At this point the player will have to spend the lab's keys and locks to it's fullest by going back up to the roof one last time to get the valve, use the valve to fill a beaker with water and repair a Bunsen burner to make the acid. Also, the troll key from the attic finally finds its use. While this completes all the locks in the lab, there is still one key left which the player must obtain to solve the rest of the game: The vial must be filled with water to be used on a large... egg in the second tomb.
And thus the real game begins, and we still don't have a clear main objective. I think this was a good choice for this game, it further fuels the curiosity of the player, which the player will need at this point if he/she is going to bother to check all the areas thoroughly. I also think it's very interesting design wise how the ancient section (1) is much larger on the graph compared to the other locations. It is like a miniature game of its own. Again, I think this was a great design choice. If this is the first location the player chooses to go to, it eases the shift in gameplay style from basic puzzle solving to location jumping, slowly escalating the challenges. I don't think this is a random design decision either, look at the sixth location, the ship and notice how it serves as a final gauntlet for the player. The golden arm is one of the most labor intensive items to get in the game, getting the chest key requires that the player completes both the basement section (3) and the looping traps (2), and obtaining the turbine requires completion of the lighthouse digouts (4). The golden sceptre puts the player through much less work, but is also guarded by two of the most cryptic puzzles in the game: you need to realize the three symbols (circle, square, triangle) is a coordination code, and removing the egg shell sees the player going all the way back to the lab. If the player hasn't solved these puzzles before obtaining the arm, it serves as an excellent final challenge.
Third, and last, the player must also find three new subnet coordinates by reading notes and searching for clues in the subnet (there are also two optional coordinates for even more adventurous players). One of these coordinates takes the player to the final objective of the game: Repair the broken statue. This coordinate is obtained from solving all of the ancient section, bringing the fuse to the basement section and fueling it to light up the beacon (this further proves the point that the ancient section is used to ease the player into the subnet travelling puzzles: the last puzzle of the ancient section is the only one to involve subnet travelling, and it is a really simple puzzle).
Giving the statue its arm and scepter completes the game.
I think it is safe to say that submachine 4 stands as one of the crowning achievements of the series. The game cleverly plays with expectations and spreads the keys and locks excellently to create a surprising, creative and satisfying experience. If this game doesn't capture the essence of being an explorer, I don't know what game does.
Tune in tomorrow for the dungeon graph breakdown of Submachine FLF