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Bloons TD 6 guides for every map and mode, daily challenges and the BTD6 Pedia

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Underground

Advanced map

Underground guides for every mode

Underground is a advanced map in Bloons TD 6. Below are our guides for all 15 modes on it, each with the towers, hero and upgrade order from a game we won. Pick the mode you need, or start with Easy and work up to CHIMPS for the black border.

Easy

Medium

Hard

About Underground

Underground is short and fast, but it is generous with good spots. The centre of the map, and the space directly above and below it, reaches both lanes, so most of your defence can sit in one compact cluster.

Put Sauda or a Dart Monkey in the centre, add a Boomerang Monkey and a Tack Shooter beside it. Get camo by round 24, and a 3-2-0 Glaive Ricochet or 0-3-2 MOAB Mauler for round 40. Finish with Glaive Lord.

Underground in the BTD6 Pedia: layout, best heroes and strategy →
Win CHIMPS on Underground with this all-or-nothing strategy. No continues, extra lives, or income make each decision critical in CHIMPS mode. This guide provides exact placements and upgrades to tackle each wave, ensuring victory on Underground in CHIMPS mode.
Beat Impoppable on Underground with precise tower placements and upgrades. Impoppable’s increased difficulty requires a well-coordinated defense, and this guide offers key strategies to clear each wave on Underground.
Conquer Half Cash on Underground with budget-efficient tower placements. Limited income makes strategic choices essential, and this guide offers cost-effective setups to stretch every dollar and secure victory in Half Cash mode.
Master Alternate Bloons Rounds on Underground with this balanced approach. The variety of bloon types requires versatile defenses, and this guide provides optimized setups to manage each wave effectively on Underground.
Win Double HP Moabs on Underground with fortified setups that handle extra-tough MOABs. Double-strength MOABs make each round more challenging, so follow this guide for tower placements that counter the increased difficulty on Underground.
Beat Magic Monkeys Only on Underground with carefully positioned magic towers. The tight paths of Underground make tower positioning critical, and this guide provides key strategies to handle each wave effectively with magic towers.
Master Military Only on Underground with this specialized approach. Underground’s confined paths make military tower positioning essential, and this guide provides optimized setups to secure victory with only military towers.
Survive Apopalypse on Underground with this high-efficiency strategy. The nonstop bloon waves in Apopalypse mode make tower placements critical, and this guide provides setups to manage continuous bloon pressure on Underground.
Complete Reverse mode on Underground by adjusting for the reversed path. Underground’s layout requires specific adjustments in Reverse mode, and this guide provides key placements to handle the waves from the opposite direction.
Master Deflation on Underground by making the most of limited starting cash. This guide provides essential tower placements to manage all bloon waves without additional income, ensuring a stable defense throughout Deflation mode on Underground.
Win Primary Only on Underground using only primary towers. The tight and winding paths make tower choice crucial, and this guide offers optimized setups to handle each wave effectively with primary towers.
Conquer Underground beyond Level 100 in Hard mode with this advanced strategy. Extended rounds on this challenging map require adaptable placements, and this guide provides setups to push past Level 100 successfully.
Win Hard mode on Underground with carefully chosen tower placements and upgrades. This guide provides budget-conscious setups to manage tougher bloon waves, ensuring a reliable defense on Underground.
Beat Medium mode on Underground with cost-effective placements and upgrades. This guide provides budget-friendly strategies to tackle each wave, ensuring a smooth run through Medium difficulty on Underground.
Conquer Easy mode on Underground with this foundational setup. Underground’s unique tunnels and tight paths require strategic tower placements to control bloon waves effectively. Use this guide to build a reliable defense and complete the map with ease.