It’s a nice engine, it’s easy to grasp and it looks good, but… 
I think you don’t do enough to drag me (the player) into the game. Its my three guys, some sparse enemies, then what? Where does it end? What should I aim for? (these are not questions, it is what I think when playing the game).
I want to know what to expect. Is this game going to be over in 20 minutes, 20 hours or 20 days? Make one level, but make it hard. Give some hints about this. Make it short but challenging.
I played another roguelike found here, one I like very much. You start in the town and you can browse the shop. You see how much gold you have and you see the overall prices. Instantly you can see how much gold you need to buy the best weapon in the shop, so you know what to expect in terms of game length. Also, it makes you eager to go out and kill things so you can come back and shop.
Show something nice, that you can’t get, yet. How about a locked door and a prize behind it. Go find the key. Or a room opposite some impassable terrain, with some guy you need to rescue. You have to find a way around.
The combat in your came doesn’t strike me as very tactical.
Some suggestions:
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Lots of weak enemies that gather around you fast and try to separate your party. You have to kill them faster than they come in then find a good spot. It you let each of your party members be crowded, you are wiped out. This also calls for a more interesting map.
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Few very strong but stupid enemies. If you meet them head to head, you will die. You have to select a good spot to face them. Someplace where the terrain works in your favour. Lure them to walk over lava or into holes.
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Make it harded to use the ranged attacks. The wizard could be more frail, have shorter range, and do more damage. You have to get in close, be protected by the meat shield and then unleas your blast. The ranger should do more damage, but after an attack he will stand still and reload the next turn.
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Play the game, with some more interesting enemies, try to find an optimal strategy. Invent an enemy that counters that strategy.
In my own roguelike I had the following more advanced enemies:
- Shooter. It looked onto your current position and started to count down. After a certain amount of time it blasted that tile to oblivion. Kind of like a timed grenade. It made you want to move, fast! And moving wasn’t always practical, you had to choose.
- Engineer. This unit carried a sentrygun. Once it saw you, it took a turn setting up the sentrygun. The sentrygun started firing while the engineer retreated to it’s hiding place for another sentrygun. You hade to choose whether to blast the sentrygun or chase the engineer before he came back with the next sentrygun.
- Ninja. Invisible and with very high movement until it attacked. There is no place to hide and rest. The ninja will catch up and finish you off.
- General. A unit that only tried to get away. If it did get away, it disapeared. If you managed to stop him you got a big reward.
etc…
Just some ideas…