JS1k: The JavaScript code golfing competition

CR=e=>e.getBoundingClientRect();TN=t=>b.getElementsByTagName(t);PX=s=>s+'px';ST=setTimeout;SQ=n=>n*n;AN=(p,l,s,b)=>`<a style="top:${p}px;left:${p}px;border-radius:${l/2}px;position:absolute;width:${l}px;height:${l}px;transition:all ${s}s;background:#${b};"></a>`;MG=(m)=>M.innerText=m;BG=s=>b.style.background=s;BG('#000');b.style.overflow='hidden';b.innerHTML=AN(0,200,2,"fff")+AN(94,12,15,"a00")+'<b style="float:right;color:#fff;margin:1em;font-size:22px;">';P=TN('a')[0];T=TN('a')[1];M=TN('b')[0];MG('CHASE THE RED DOT');R=125;E=0;onclick=e=>{P.style.top=PX(e.clientY-R);P.style.left=PX(e.clientX-R);};setInterval(()=>{if(!E){p=CR(P);t=CR(T);r=p.width/2;if(SQ(p.top+r-t.top-6)+SQ(p.left+r-t.left-6)>r*r){BG('#a00');T.style.display='none';E=1;MG('YOU LOSE');}}},20);f=(x,y)=>{R-=25;P.style.width=PX(R*2);P.style.height=PX(R*2);T.style.left=x;T.style.top=y;};ST(f,300,'94px','95%');ST(f,10000,'50%','10px');ST(f,18000,'95%','95%');ST(()=>{if(!E){E=1;BG('#048');MG('YOU WIN');}},32000);

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// Click and Chase (JS1k 2018 entry)
//
// A browser game to chase a moving red dot with your mouse. If you can keep
// the target within your sight for more than 30 sec, you win!
//
// Note
// ----
// The key of this game is CSS transition. It introduces some delays between
// user inputs and visual outputs, and makes it hard to navigate the "spot
// light" along with the moving target. This delayed feedback makes this game
// somewhat enjoyable.

// Shorthand functions
CR = e => e.getBoundingClientRect();
TN = t => b.getElementsByTagName(t);
PX = s => s + 'px';
ST = setTimeout;
SQ = n => n * n;
AN = (p,l,s,b) => `<a style="top:${p}px;left:${p}px;border-radius:${l/2}px;position:absolute;width:${l}px;height:${l}px;transition:all ${s}s;background:#${b};"></a>`;
MG = (m) => M.innerText = m;
BG = s => b.style.background = s;

// Set up the game screen
BG('#000');
b.style.overflow = 'hidden';
b.innerHTML = AN(0,200,2,"fff") + AN(94,12,15,"a00") + '<b style="float:right;color:#fff;margin:1em;font-size:22px;">';
P = TN('a')[0];
T = TN('a')[1];
M = TN('b')[0];
MG('CHASE THE RED DOT');

R = 125; // Radius of the spot light
E = 0;   // The end-game flag

// Callback for moving the spot light
onclick = e => {
    P.style.top = PX(e.clientY - R);
    P.style.left = PX(e.clientX - R);
};

// Check if the target remains within player's sight (every 20ms)
setInterval(() => {
    if (!E) {
        p = CR(P);
        t = CR(T);
        r = p.width / 2;
        if (SQ(p.top + r - t.top - 6) + SQ(p.left + r - t.left - 6) > r * r) {
            BG('#a00');
            T.style.display = 'none';
            E = 1;
            MG('YOU LOSE');
        }
    }
}, 20);

// Define the game scenario
f = (x, y) => {
    R -= 25;
    P.style.width = PX(R * 2);
    P.style.height = PX(R * 2);
    T.style.left = x;
    T.style.top = y;
};

ST(f, 300, '94px', '95%');
ST(f, 10000, '50%', '10px');
ST(f, 18000, '95%', '95%');
ST(() => {
    if (!E) {
        E = 1;
        BG('#048');
        MG('YOU WIN');
    }
}, 32000);