diff --git a/src/Unaboomer.sol b/src/Unaboomer.sol
index de23585..d06aafc 100644
--- a/src/Unaboomer.sol
+++ b/src/Unaboomer.sol
@@ -21,6 +21,8 @@ contract Unaboomer is ERC721, Owned {
     mapping(uint256 => bool) public tokenDead;
 
     uint256 public constant MAX_SUPPLY = 10000;
+    uint256 public constant SURVIVOR_COUNT = 1000;
+    uint256 public killCount;
     uint256 public minted;
     string public aliveURI;
     string public deadURI;
@@ -73,7 +75,10 @@ contract Unaboomer is ERC721, Owned {
     function kill(uint256 tokenId) external {
         require(msg.sender == address(main), "invalid minter");
         require(tokenId < minted, "invalid token id");
-        tokenDead[tokenId] = true;
+        if (tokenDead[tokenId] == false) {
+            killCount++;
+            tokenDead[tokenId] = true;
+        }
     }
 
     function totalSupply() public view returns (uint256 supply) {
diff --git a/src/UnaboomerCommon.sol b/src/UnaboomerCommon.sol
index 1b143bd..3be45fc 100644
--- a/src/UnaboomerCommon.sol
+++ b/src/UnaboomerCommon.sol
@@ -56,12 +56,21 @@ contract UnaboomerCommon is Owned {
         mailbomb = Mailbomb(_address);
     }
 
+    // =========================================================================
+    //                              Modifiers
+    // =========================================================================
+
+    modifier missionCompleted {
+        require(unaboomer.killCount() <= unaboomer.SURVIVOR_COUNT(), "mission already completed");
+        _;
+    }
+
     // =========================================================================
     //                              Tokens
     // =========================================================================
 
     /// Radicalize a boomer to become a Unaboomer
-    function radicalizeBoomer(uint256 _amount) external payable {
+    function radicalizeBoomers(uint256 _amount) external payable missionCompleted {
         // check if game halted
         require(msg.value >= _amount * boomerPrice, "not enough ether");
         unaboomer.mint(msg.sender, _amount);
@@ -69,25 +78,17 @@ contract UnaboomerCommon is Owned {
     }
 
     /// Assemble additional mailbombs to kill targets
-    function assembleBomb(uint256 _amount) external payable {
+    function assembleBombs(uint256 _amount) external payable missionCompleted {
         // check if game halted
         require(msg.value >= _amount * bombPrice, "not enough ether");
         mailbomb.mint(msg.sender, _amount);
     }
 
-    /// Kill random targets with mail bombs
-    /// @dev Function returns a boolean depending on if Boomer was already killed or not - i.e. if dud
-    /// @dev The likelihood of killing a boomer decreases as time goes on - i.e. more duds
-    function killBoomer(uint256 tokenId) private returns (bool isDud) {
-        bool dud = unaboomer.tokenDead(tokenId);
-        unaboomer.kill(tokenId);
-        return dud;
-    }
-
     /// Send N bombs to pseudo-random Unaboomer tokenIds to potentially kill them.
     /// If the Unaboomer is already dead, the bomb is a dud.
     /// @dev Pick a pseudo-random tokenID from Unaboomer contract and toggle a mapping value  
-    function sendBombs(uint256[] calldata tokenIds) external returns (bool[] memory results) {
+    /// @dev The likelihood of killing a boomer decreases as time goes on - i.e. more duds
+    function sendBombs(uint256[] calldata tokenIds) external missionCompleted returns (bool[] memory results) {
         require(tokenIds.length <= mailbomb.balanceOf(msg.sender));
         bool[] memory res = new bool[](tokenIds.length);
         uint256 boomerSupply = unaboomer.totalSupply();
@@ -95,8 +96,9 @@ contract UnaboomerCommon is Owned {
             require(mailbomb.ownerOf(tokenIds[i]) == msg.sender, "token not owned");
             uint256 randomBoomer = uint256(keccak256(abi.encodePacked(tokenIds[i], block.timestamp, msg.sender))) % boomerSupply;
             mailbomb.burn(tokenIds[i]);
-            bool _res = killBoomer(randomBoomer);
-            res[i] = _res;
+            bool dud = unaboomer.tokenDead(randomBoomer);
+            unaboomer.kill(randomBoomer);
+            res[i] = dud;
         }
         return res;
     }
diff --git a/test/Unaboomer.t.sol b/test/Unaboomer.t.sol
index f2c87cb..19a7c05 100644
--- a/test/Unaboomer.t.sol
+++ b/test/Unaboomer.t.sol
@@ -29,7 +29,7 @@ contract UnaboomerTest is Test {
 
     function testMint() public {
         hoax(address(1));
-        main.radicalizeBoomer{value: 0.05 ether}(5);
+        main.radicalizeBoomers{value: 0.05 ether}(5);
         assertEq(boomr.totalSupply(), 5);
         assertEq(boomr.tokenDead(1), false);
     }