Unfortunately, a release by Christmas is looking unlikely, since I have still to finish the first character and make all the sprites, sound effects, UI e.t.c. I have actually been working as I can on this, but unfortunately it's exam season so it's a bit on-and-off. However, I can show you some of the fighter mechanics so far.

The Human uses typical undertale weapons in their normal attacks (such as the stick or frying pan) however in their special attacks, they make use of their soul.

Frisk's soul follows closely behind them and will change colour and position based on the current attack. For example, in the up special, the soul becomes blue and pulls the fighter in the direction of the joystick / arrow keys in a dash-like move.

(This attack sprite hasn't been made yet so just imagine Frisk is flying or something, not just standing like an NPC)

The soul will also react to attacks by other fighters. For example, I plan on giving Sans a gravity attack. In this situation Frisk's soul will turn blue like in Undertale. The soul is independent to the Human so other characters won't have one (unless context means that they should, e.g. any fan-made characters) Sans and Undyne will be the only other characters in the first beta but there will be many more afterward!

I originally was thinking of getting somebody else to do sprites for me, and I spoke to a few people. In the end I decided to do this myself, at least in the earlier stage of the game. I want to improve my pixel art skills anyway so this is a good way to do that I think.

That's all, merry christmas :}