I think the best improvement they could make would be a detailed map. Keep the live action map, but add a pause screen map so you could tell what buildings that you've already painted.
Also, different colors could give De Blob different abilities: Blue makes you jump higher, red makes you attack better, green makes you go faster. yellow makes you slide on walls longer, etc. This would go a long ways in adding variety to the gameplay and make getting all of the awards for the levels more challenging.
Ever notice how "hardcore" gamers are always whining like little children?
Maybe if they had some better multiplayer kinda things, too. =/ That'd be nice. xD And if they make it so you can't get stuff. Either just with the coding kinda stuff, or with something that allows you to fix it if you get stuck, like a 'go through walls' kinda thing, or something. xD