Tower Siege Strategy: Best Tiles, Upgrade Value and Wave Math

Updated October 2026

Tower Siege gives you one winding road, twenty lives and an endless line of enemies that get tougher every wave. There is no way to win outright; the question is how deep you can go before the defence breaks. Because the map is always the same and the only randomness is the mix of enemy types in each wave, shown before the wave starts, a run is a planning problem more than a reflex test. This guide breaks down the map, the cost of every tower and upgrade, and how the waves scale, then turns those numbers into a build order you can refine from one run to the next.

The map and the rules that matter

The field is 11 tiles wide and 15 tall. The road enters at the green square on the left of the second row and snakes back and forth across the board, doubling back on itself four times, before leaving at the red square near the bottom right. It covers 55 tiles and is 54 tiles long from end to end, which leaves 110 tiles you can build on. Any tile that is not road can hold a tower, including the outer edges, though those are rarely worth it.

The first wave starts four seconds after you press Start, and there is a pause of four and a half seconds after each wave is cleared. The Start button in the bottom bar sends the next wave early, and the speed button toggles double speed; while a tower is selected, the bar keeps a small ▶ button for the next wave next to Upgrade and Sell. You begin with 95 gold and 20 lives. Every enemy that reaches the red square costs one life, and the game ends the moment the last life goes. Your score is the number of the wave you were on at that moment, plus the share of that wave you had destroyed, so two runs that fall on the same wave are still told apart. It is shown as the wave and a percentage, for example 27 · 64%.

Where to build: road coverage by tile

A new tower reaches 2.6 tiles in every direction and always shoots the enemy that is furthest along the road among those in range. What makes a tile valuable is how much road lies inside that circle, since that decides how long each enemy stays under fire. We measured it for every buildable tile.

• The best tiles see about 10 tiles of road. They sit in the narrow two-row strips between parallel stretches of road, one or two tiles in from the end where the road turns back. From there a tower covers the road above, the road below and part of the bend.
• In each strip, the upper row is stronger. Tiles in the upper row of a strip typically see 9 to 10 tiles of road, while the row beneath sees 7 to 8.
• The middle of the board is the median. A typical buildable tile covers about 6 and a half tiles of road.
• The outer ring is poor. Tiles along the outside edge and the bottom row cover only 2 to 5 tiles.

Enemies on wave one move about 1.7 tiles per second, so an enemy walking past a top tile spends close to six seconds in range. At one shot every 0.45 seconds, that is around a dozen shots from a single tower, against an outer-edge tile that might get three or four.

What gold buys

A tower costs 55 gold and deals 9 damage per shot. Upgrades cost 40 for the first, then 30 more for each one after it: 40, 70, 100, 130 and so on. Each upgrade adds 8 damage and a small 0.12 tiles of range. Selling returns half of everything you put into that tower, including upgrades.

Divide damage by price and a clear pattern appears. The first upgrade is the best deal in the game, at 8 damage for 40 gold. A brand-new tower on a top tile comes next. The second upgrade costs 70 for the same 8 damage, and every upgrade after that is worse still, because the cost keeps rising while the damage stays fixed. Your starting 95 gold is exactly one tower plus its first upgrade, which is a strong opening on a top tile.

That arithmetic favours spreading out over stacking. In our simulation, a simple bot that bought whichever option gave the most damage per gold on the best available tiles reached wave 23 to 24 when limited to 4 towers, 26 to 28 with 8 towers, 28 to 30 with 12 and 32 to 34 with no limit (the spread comes from the random wave mix). More towers on good tiles beat fewer towers with high levels, at least until the good tiles run out.

How the waves scale

Wave number n sends 8 + n enemies, spaced 0.55 seconds apart. A normal enemy has 11 × 1.155ⁿ health, rounded, and walks a little over one percent faster per wave; fast and tough enemies from wave 3 on scale those two values as described below. Kills pay 1 gold, plus another gold for every fourth wave: 1 gold each up to wave 3, 2 from wave 4, 3 from wave 8, and so on.

Put those together and the shape of every run becomes clear. Health grows by 15.5 percent per wave, which compounds; at wave 10 an enemy has 46 health, at wave 20 it has 196 and at wave 30 about 830. Income grows only steadily with the number of enemies and the slowly rising bounty. Early on, each wave pays more than enough to cover the next one. Somewhere in the twenties the curves cross, and from then on every wave is harder relative to your gold than the one before. That is where runs end, and where planning pays off most.

A build order to start from

1. Place your first tower on one of the top tiles beside the first turn, and upgrade it once straight away with the remaining 40 gold.
2. Add towers on the next-best tiles further along the road as gold arrives, giving each one its first upgrade before buying a second level anywhere.
3. Keep at least one strong tower on the last two stretches of road. Enemies that slip past the early towers need to meet fire again before the red square.
4. Once the top tiles are taken, alternate between second upgrades on your best-placed towers and new towers on the median tiles.
5. Sell outer-edge towers you placed in a hurry and rebuild that gold on a better tile; you lose half, but a top tile can see three times as much road.

Using a fixed map to your advantage

The road, the base health and speed of each wave, the gold values and the timings are the same on every run. What changes is the mix: from wave 3 each wave swaps a random share of its enemies for fast ones (») with 60 percent of the health and 1.6 times the speed, and slow, tough ones (■) with 1.7 times the health and 0.65 times the speed. The line at the top of the board shows the next wave before it starts, so a wave full of fast enemies is a cue to make sure the late stretches of road are covered, while a tough-heavy wave rewards concentrating damage. Towers fire at the same rate at any frame rate and at double speed. Note the wave where your last run broke and which stretch of road leaked first, then change one decision next time, such as an earlier tower on a lower strip, and compare. Sending waves early only helps while you are comfortably ahead; it does not earn extra gold by itself, so when lives start to drop, let the pause run and spend first. Your best score stays on your device, and any score above zero can be saved to the Hall of Fame from the game-over card.