A bit buggy, linear, and in need of spellcheck.
I found 3 bugs in the single play through that I did, which is quite a few for a 3-4 minute game with such simple mechanics.
1. I had considerable trouble filing through the gates after obtaining the nail file, it seemed I had to be in the exactly perfect spot for it to register the action. (Apparently fixed)
2. The thirsty guard's dialog automatically resets, but without the box, it's just letters on the background and you can continue the entire conversation, it doesn't go away until you hit space and go back.
3. The ice that you get to fill the cup respawns and shows the action button after being melted, but can't be used again.
Now, on to the suggestions.
First off, spell check every piece of dialog you put in the game, grammar check it as well. It gives a much more professional and polished feel, and while it may not be noticed when it IS there, it's definitely noticed when it isn't.
Second, I suggest making things a little less obvious. Maybe remove the character's thoughts or make them more vague, rather than instantly supplying the solution to the puzzles.
Third, give the player an option to use the arrows/WASD keys to select dialog options, and a key to open the inventory(assuming you intend to expand it in the future). This allows the player to choose whether or not they want to play with just the keys or with the mouse as well, and giving the player an option to do it their way is always better than forcing one specific method on them(designers and developers provide key binding options for a reason).
Additionally, you could make the guards a bit less eager to be of assistance to an obviously escaping prisoner, one guard practically stares you down as you file your way through the bars and then gives you directions.
Finally, extend the game a bit, it was incredibly short(3-4 minutes long). Maybe let the player explore a bit more, even if it's only empty rooms or cells with NPCs who tell stories/expand upon the story.