Welcome to NEMonsters, a witty little collection game based on the NEM blockchain. You can catch and collect over 110,000,000 different combinations of generated monsters; spanning from different colors, names and other spicy characteristics. You catch a new monster by sending a fixed transaction; the monster is summoned when the transaction is confirmed. The characteristics of your new (evil) monster is based on the transaction hash – how cool is that. See if you can catch some of the monsters from the NEM foundation.

The purpose of NEMonster is

• to have fun
• to demonstration how you can own non-tokenized assets on the blockchain utilizing off-chain and on-chain logic
• to show how you can use the unique hash of an transaction as a means of procedural generating an gaming asset.

NEMonster is a browser-based game, implemented as a NEM NanoWallet module, it can be found under the tab services.

The making

We are looking at outgoing transaction, finding relevant transactions to the monster recipient address. The hash data for relevant transactions are saved in a array.

$.each(data, function( index, value ) {
    //change if multisig
    if (value['transaction']['type']==4100){
        var value2 = value['transaction']['otherTrans'];
    }else{
        var value2 = value['transaction'];    
    }
        // loop transactions to find catch trans                
        if ( value2['recipient'] == recipient){
        //minimum 0.5 xem 
        if((value2['amount']/1000000) <= 0.5) {
            potentialMonsterHash.push(value['meta']['hash']['data']);   
        }                       
    }                                                   
});

The hasharray is then analyzed and each hash is rehashed a couple of times with the purpose of making the hash a seed for procedural generating different attributes for the monsters:

var colors = ['#F45B69', '#4286f4', '#42f4b6', '#8941f4', '#f49d41', '#ce3333', '#a9ce33', '#33ce35', '#338ace', '#ce3385','#f4ce42','#cee5ce'];

var hash = this.hashStr(potentialMonsterHash[index],5381);
var ind = Math.abs(hash % colors.length);
...
Monsters[index] = {
color : colors[ind],
monster : monster[ind2],
hair : hair[ind3],
eyes : eyes[ind4],
iris : iris[ind4],
mouth : mouth[ind5],
teeth : teeth[ind6],
nam1 : nam1[ind7],
nam2 : nam2[ind8],
grad : grad[ind9],
grad2 : eyecolor
};