JavaScript
(function(elid, wi, he, exp, pot, gld, hp, lvl, cur_e, e_sz){
var hit = function(){ evs[cur_e][8]-=lvl*4+6; if(evs[cur_e][8]<=0) {
alert("Monster defeated and you got "+evs[cur_e][10]+"EXP and $"+evs[cur_e][11]);
exp+=evs[cur_e][10];gld+=evs[cur_e][11]; while(exp>=lvl*10){exp-=lvl*10;lvl++;alert("Level Up!")}
cur_e++; if(cur_e==e_sz) alert("Victory!") } else {
hp-=Math.max(0,evs[cur_e][9]-lvl*2-1); if(hp<=0) alert("Game Over!") } }
var use = function(){ if (pot>0){pot--;hp+=10;if(hp>100)hp=100} }
var nxt = function(){ cur_e++ }, battle = ["Attack","Use Potion +10HP","Skip Battle",hit,use,nxt],
canvas=document.querySelector(elid), ctx=canvas.getContext("2d"), evs=[], e_tp=[
["Shop", "Wizard provides his services", "Buy Potion $20", "Full Heal $100", "Leave",
function(){ if(gld>=20){gld-=20;pot++} }, function(){ if(gld>=100){gld-=100;hp=100} }, nxt ],
["Skeleton", "A terrible skeleton on your way"].concat(battle,70,15,25,100),
["Goblin", "Green goblin wants to get your money"].concat(battle,50,10,15,70),
["Slime", "What the strange jelly monster?"].concat(battle,20,6,7,30),
["Dragon", "Omg! It is evil Dragon!","Attack","Use Potion +10HP","-",hit,use,,300,25,100,1000 ] ],
q=e_tp.length-1; canvas.width=wi; canvas.height=he; for (var i=0;i<e_sz-1;i++)
evs.push( e_tp[Math.floor(Math.random()*q)].slice(0) ); evs.push( e_tp[q].slice(0) );
var game = setInterval(function(){ ctx.clearRect(0,0,wi,he);
ctx.fillText("NanoRPG in 30 lines of JavaScript by ripatti",10,15);
ctx.fillText("LVL "+lvl+" HP "+hp+"/100 EXP "+exp+"/"+lvl*10+" ATK "+(lvl*4+6)+
" DEF "+(lvl*2+1)+" Gold $"+gld+" Potions "+pot,10,30);
for (var i=0;i<e_sz;i++) ctx.fillText((i==e_sz-1||i<=cur_e)?evs[i][0]:"??",i*50+15,70);
ctx.fillText("@",cur_e*50+25,60); ctx.fillText(evs[cur_e][1],20,100);
if (evs[cur_e].length>8) ctx.fillText("Enemy HP "+evs[cur_e][8],250,100);
...