Hustle Chumy

Hustle Chumy(Sometimes spelt as Hustle! Chumy) was a 1984 action game by Compile and Sega for the SG-1000

Plot
Chumy is a rat who lives in the sewers, who needs to collect food. However the sewers are crawling with antagonists who want to prey upon her! Cats, bats, alligators and even ninjas and mecha dinosaurs will get in her way for dinner.

Gameplay
Players play as a little rat named Chumy. The goal of the game is to collect all the food in the level and return to your mouse hole.

Chumy must climb ladders and use pipes to get to and from the different levels, whilst avoiding enemies. Chumy isn't completely helpless however as she can shoot fireballs(or possibly tin cans) at enemies to defeat them.

The twist in the game mechanics is that as Chumy eats more food, she becomes less agile, slowing down with every single snack, although in exchange Chumy's fireballs have more range and can defeat enemies more efficiently as a result.

Jumping ends up being a more efficent way to get around as Chumy's airspeed remains the same as she jumps, making hopping preferable to walking.

Trivia

 * This was the first game Kotaro Hayashida, creator of Alex Kidd, worked on.