People keep coming back to Idle Mine because it has a nearly unreachable end. You should add layers to the final planet to keep people playing. Peel one back, move on to the next that has more HP and worth.
Damage should be kept as high as possible. Range should only be improved to reach a target. Auto-fire should be kept as high as possible. If you are not clicking, max shots should be kept between 2x and 3x of auto-fire depending on the target distance. If you are clicking it needs to be as high as you can get them out.
It looks like you have chosen the Dodo as the enemy of the penguin; I'd recommend you change this to the Great Auk. It is another extinct bird, and the penguin, despite not being related, has a lot of similarities to it. In fact "Penguin" was first used to describe this bird, but since its extinction we use it on the Antarctic birds. Very suspicious!
Bullet travel speed (does not affect distance) really bugs me. Initial velocity is the greatest decider in the travel distance of a launched object. No wonder your penguin can fly, the physics of your universe don't make any sense.
This sequel needs an Action-RPG system. A randomized (but based on distance) mix of enemy spawns, and equippable/upgradable weapons, tires, chassis, engines, secondary support, etc. It'd be pretty cool.
Please upvote this so people stop spamming the dev's page: If you delete your history or your cookies, etc. you might lose your save progress. This is not the dev's fault. Stop spamming him with your whining. Blame yourself or blame Adobe for making flash saves work this way. If you play this game a lot, don't delete history or back up your saves.
I'm positive that most complainers on daily badges don't look at publish dates. This came out in 2009, guys. You're whining about a lack of features that weren't standard in flash games at the time. This game had some cool new ideas, it wasn't missing" things, it was ahead of the curve.
Why are people tagging this an idle game? You are scored based on your finish time and cannot earn and finish as quickly without jumping/flying for coins. That means that it is NOT an idle game.
To kill the boss do the following: Get rid of all the crates and explosives with one molotov. When the boss spawns, start shooting him in the head with normal bullets until he is DIRECTLY under the acid. Save one bullet. Shoot the switch with it. He should go down to about 20% health. Throw the rest of your molotovs as dead center on his head as possible. Finish him off with head shots from the tesla. You should not need any grenades (they suck against him)
Well I was going to say "at least this has original art assets" but I am pretty sure that ground and background are from Sonic the Hedgehog, so yeah...
Finished the game with all stars. Like the game says at one point, you CANNOT get some stars without upgrades. The game gives enough money to just get all upgrades (with about 5k left over). Just keep progressing through the levels. When one gets too hard, go back to the earliest level you don't have all stars on and try again. Got through the game no problem with this strategy.
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Thinking about adding this, but I don't know how feasible it'd be with increasing distance. Maybe in the next big update :P