it's a simple game and does get quite boring after a while.

could use work

its a good concept but it needs to have maybe levels or progressively longer code combinations

Nice

Very graphically basic game, but seems functional enough. I scored 63 I think before I just got tired of the same thing over and over. It didn't look like the levels would ever progress or anything would change at that point. Nonetheless, I haven't seen a game designed like this before. There may be one, but I haven't seen it so I give you points for originality, and a fully functionally basic game ;)

Not bad for what it is

There's definitely room for more features, to make it more addictive. Music, obviously, but what it really needs is a difficulty curve. Over time give us more doors and/or longer number sequences, and maybe have the length of time for which we get to see the numbers get marginally shorter over time. Some better graphics wouldn't hurt, but they're certainly not a necessity for a game like this.

Really though, give it a relaxing loop of music and a difficulty curve, and you'll have an addicting game here. Just be sure to make each door worth more points as the difficulty goes up, to make sure the score scales with the difficulty.