by nerman8r
If you look through the variants other people have posted, I think you might find something better. I think the having-to-stay-in-Tokyo-until-your-next-turn mechanic is where a lot of the fun in the game is. I'd recommend this: in a 4 or 5 player game, a player who starts their turn in Tokyo gains an energy cube, and in a six player game, that player gets 2 energy cubes, in addition to the 2 victory points.One concern I have with this variant is that it discourages people from attacking the monster in Tokyo, for fear of giving her/him more points.
With the original rules, if a beefy monster is in Tokyo, the other monsters usually gang up to knock them down. Players generally aren't too inclined to try to roll tons of claws against a monster with 7 or more health, because then they can't get hearts, energy or victory points for themselves.
Your variant makes there less incentive to poke at the monster in Tokyo for one or two damage, because you're also giving them a victory point. So, if someone is going to attack the monster in Tokyo, they're going to have to go big, which is risky because you can't always count on rolling a lot of claws.
The reason I suggest giving out extra energy instead of victory points is because I don't think the game needs to be any shorter. If the game is shorter, buying Keep cards becomes less useful, since they won't have as much of a chance to impact the game.