Bloons TD6 - Geared CHIMPS (Version 40.2)

This setup is fast and has basically no RnG as long as you time Obyn's abilities properly. It's crucial to manage target priority correctly for the first 50 rounds to maximise pierce (especially the first 30 rounds). Make sure that towers on the left side of the track are set to 'Last' as in the video, towers on the top typically to either 'Last' or 'Strong', and the rightmost towers near the exit to 'First' to prevent leakage.
Some important points:
0:07 Make sure to place the initial Sniper here and not in any random location to allow it to be buffed by a Monkey Village later on.
2:55 Obyn needs to be placed before the Green rush at the end of Round 17.
3:35 Use Brambles during Round 21 just before the Pink rush, but not earlier.
3:53 This Sniper for Round 23 needs to be placed away from the other towers so that it doesn't harm Monkey Village / Alchemist placements later in the game. Make sure to set it to 'Strong' priority.
4:06 Don't forget to click on Camo priority once you get Night Vision Goggles.
4:29 The last Sniper for Round 25 needs to placed midway through the round as fast as possible to prevent yourself from dying. Keep it on 'First'.
4:55 You need to use Brambles before the Yellow rush on Round 27.
5:08 Once you get Druid of the Jungle, change its target priority back to 'First'.
5:19 Change the 1-2-0 Sniper's priority to 'First' for Round 33 (and 40); keep that Sniper's priority on 'Strong' otherwise.
6:07 The Heli Pad on Round 36 needs to be placed near the imaginary radial line between Obyn and the centre of the gear, but offset a bit close to the 1-2-0 Sniper. This is needed so that there's a spot for a 0-2-4 Glue Gunner to fall within the Monkey Village range by the time Rounds 98 and 99 come along.
6:10 Use Brambles on Round 37, specifically before the Camo White wave at the very end to help clean them up.
6:57 This 0-0-2 Bomb Shooter is only needed to clear the Ceramics on Round 40.
7:29 You need to get a second 1-3-0 Druid in range of Obyn in preparation for/during Round 43 to help clear the Ceramics.
7:39 Make sure Brambles is on the track for Round 45 to clear the Camo Purples.
11:00 Keep refreshing Wall of Trees each time the gear makes a revolution - on the right side of each to act as a stall barrier. This is especially important for Round 63; activate Wall of Trees on an earlier round to ensure the wall soaks up excess Bloons.
18:14 Keep the 3-0-1 Alchemist out of range from as many towers as possible besides the Comanche Commander. This increases likelihood of buffing.
18:45 Make sure to micromanage the Mortar's firing for Rounds 96 and 98.
19:54 The 0-2-4 Glue Gunner in range of the Monkey Village is helpful for Round 98 and 99.