Where Carnival moves further from Space Invaders is that you have limited shots to fire unless you hit an extra bullets power up, and a bonus which you gain by shooting out the letters which spell "bonus" but watch when you finish it off as sometimes the bonus will be negative points, positive points, or extra ammo. You also have several pipes on a turntable at the top of the screen to take out, which the tin animals and bonus letters obscure. Sega also added an extra difficulty by having the ducks randomly take flight and head down to eat your bullets if you don’t take them out, so you can’t just take aim at the pipes and sit taking out pipes and tin animals to complete a level, you need to move to stop those darned ducks from taking your ammo.
Another nice touch is a bonus round between each level where you have to shoot what look like bears which stand up when shot and turn the other way, and run quicker each time they’re hit. If they get off the edge of the screen the bonus level is over. At each level you have more bears in play to try to keep on screen, not an easy task at all.
Carnival has some colourful recognisable graphics and good sound effects which sound like a bullet hitting a tin target (or as good as any 8 bit sound from that era gets anyway), and some jaunty fairground music playing as you blast away at the gallery animals. Gameplay is fun if a little repetitive after a time, and is occasionally let down by a poorly detected collision as your bullet hits a flying duck but doesn’t take it down, or in hitting the pipes where one bullet hits but another which looks exactly the same is a miss.
Overall a good game but gets to samey samey too quickly, although the difficulty ramps up nicely and the presentation is very good. For dodgy detection of collisions and repetition, I have to give Carnival on Colecovision a 6/10
