A random defense game in the spirit of the StarCraft custom map "Solo Luck Defense" — play free in your browser

Step by step

1. Press START and round 1 begins immediately. You start with 40 minerals, enough for four draws straight away.
2. Press Draw (Q) to spend 10 minerals; the new unit appears in the middle of the map and is selected automatically, with its grade and name announced on screen.
3. Left-click or tap a unit to select it, drag from empty ground to box-select several (hold Shift to add to the selection), and right-click (on touch, tap empty ground) to send the selection there. Groups keep their formation shrunk to 70% around the target, units never overlap and step aside to the nearest free spot, and nobody shoots while walking.
4. Attack upgrade (W) gives every unit +1 damage and costs 10 + 6 × current level (10, then 16, 22, 28…). Sell (S) trades the selected units for 4, 6, 8 or 10 minerals by grade. F cycles speed through x1, x2 and x3; ESC clears the selection.
5. The top bar shows ROUND, TIME, minerals, monsters n/100 and kills; the monster count blinks red past 60. Rounds advance every 28 seconds with bosses on 5, 10, 15 and 20. Wipe out round 20 to win, or lose when 100 monsters are on the track. The result screen takes a nickname (12 characters max) for Submit score, plus Share result and Play again.

How to play

• Monsters circle the border of the square map. They never leave until they die, and once 100 of them are on screen the game is over.
• Each kill earns +1 mineral (bosses +25). Spend 10 minerals on a random draw: Common 63.5% · Rare 26% · Epic 9.3% · Unique 1.2%. There is no merging — pure luck.
• New units appear in the middle of the map. Left-click (tap) to select, then right-click (on touch, tap empty space) to send them where you want — just like StarCraft. Units never overlap, and they can't shoot while walking.
• Damage and armor are whole numbers, StarCraft-style. Each attack upgrade adds +1 to every unit, and the price climbs each time (draws always cost 10). Monsters gain armor as rounds go up, and damage dealt = attack − armor (minimum 0.5) — skip upgrades and your commons will only scratch late-game enemies. There is effectively no unit cap (999), so select and sell the weak ones to recycle minerals.
• Enemy types: Grunts · Runners (round 3+, fast and fragile) · Armored (round 6+, slow, +2 armor, +2 minerals per kill) · Regenerators (round 9+, heal over time) · Splitters (round 12+, split in two on death and crowd the 100 cap).
• A new round starts every 28 seconds, with bosses on rounds 5, 10, 15 and 20. Kill everything in round 20 to clear the game.

Draw odds and sell prices by grade

Within a grade every unit is equally likely. The chance of at least one Unique in 10 draws is about 11%, and about 45% in 50 draws. Sell prices are below the 10-mineral draw cost, so selling to re-roll is a gamble that always loses a little.

All 21 units

Damage is shown at upgrade level 0; the interval is the number of seconds between shots. Splash deals 60% to monsters around the impact point, slow reduces the target's speed by the given share, and targets is how many monsters a unit hits at once.

Armor by round, and the monsters

Each round sends 14 + 3 × round monsters (17 in round 1, 44 in round 10, 74 in round 20) with base health of 7 × 1.27^round−1 — about 7 in round 1, 60 in round 10 and 650 in round 20 — and bosses carry 14 times that. Movement speed also creeps up every round. Armor rises by 1 every two rounds:

Type modifiers stack on top: Armored +2 (+3 from round 12), Boss +3, Runners and Spawn −1. Damage dealt is unit attack + upgrade level − armor, never below 0.5, so a 2-damage Rifleman facing the round-20 boss (armor 12) chips 0.5 per shot unless you have upgraded. Splash deals 60% to secondary targets, Regenerators heal 2% of max health per second, and Splitters break into two Spawn with 35% health when killed. Every unit targets the monster furthest along the track within its range.

It's luck, but there is technique

Early on, draw the moment you can afford it to build up numbers, and push each new unit toward the border right away — parked in the middle, its range never reaches the track. Spots near a corner cover two sides at once. Attack upgrades only pay off once you have about ten units — but from round 6, when armor kicks in, keep your upgrade level close to the round number or your shots stop landing. Epics (mechs) and Uniques (capital ships) mostly deal splash damage, which shines late when monsters bunch up, so don't dump everything into upgrades the moment one drops — fill the board first. Slowing units like the Frost Tank and Leech Mech are insurance against the 100-monster cap. When the screen turns red at 60 monsters, selling and re-drawing to gamble on a Unique is sometimes your only way out.

Leaderboard

Your score is "round reached.kills" (20.450 = round 20, 450 kills). Clears are ranked by kill count. The draw odds are rolled in your browser, not on a server, but entering a nickname on the result screen puts you on the global leaderboard.

Frequently asked questions

When should I start upgrading?

Each +1 is worth more the more units you own, and armor starts appearing in round 3. Using the table above, keep your upgrade level from falling behind round ÷ 2 and even commons keep doing damage. Since the price climbs 10, 16, 22, 28…, a late upgrade costs about as much as two or three draws.

How many units can I have?

Effectively unlimited (999). Units do take up space, though — they never overlap — so once they are pushed toward the centre their range no longer reaches the track and they idle. Put short-range commons (Flamer 90, Machine Gunner 115) right inside the border and long-range pieces (Sniper 200, Siege Cannon 210) further in to waste less room.

How many bosses are there?

Four — one each on rounds 5, 10, 15 and 20 — and each pays 25 minerals. With 14× health and +3 armor they only melt quickly to single-target hitters such as the Sniper, Siege Cannon or a Unique. A boss keeps circling until it dies and counts as one toward the 100 cap.

Are the draws decided on a server?

No. The odds are exactly as listed above and the roll happens in your browser. The only thing sent to the server is the score you submit with a nickname on the result screen.

How is the score calculated?

Round × 1000 + kills (capped at 999), shown on the leaderboard as "round.kills". Clearing round 20 gives 20.xxx, so finishers compete on kills; if you were overrun, the round reached ranks first. Your share link carries round, kills and whether you cleared, so a friend sees your score on the title screen as a target.

More free defense games

Prefer planning over gacha luck? Try the classic Tower Defense — five turret types, three maps, 30 waves and an endless mode.

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