Try Memorizing Your Paths
In Shadow Frog, it can be pretty confusing when you are being chased by your shadowy counterpart. As we mentioned, the shadow figure mimics your movements, following them every step of the way. It's easy to lose track of your exact movements sometimes.
And with the shadow on your tail, you might get a little panicky and just try to escape it. Just try remembering your path, and as the shadow follows it, you'll be able to dodge accordingly. Take advantage of the jumping abilities you have and fake out your opponent.
If you can get well ahead of it, you'll be able to separate yourself a bit and go for those keys. Early on, you'll just need to grab a key or two, so it shouldn't be too bad. Also, you have a decent amount of lives to work with as well, so don't fret if you die once or even twice. That said, don't pay attention to how many lives you have left, as this can affect your focus out there.
Take Advantage of The Walls
With Shadow Frog being an endless runner and platformer put together, you might think that there's no turning back once you go, but that's not true, actually. Since you are a frog, hopping plays a huge role in your success, and that includes utilizing the walls.
On some levels, you will need to go behind you to grab one of the keys. In order to do so, you can ricochet off of walls, allowing you to go in the opposite direction. It's a nice little way to keep the endless runner method without always going straight all of the time.
Using the walls will also let you climb to higher spots on different levels. Many times, you will notice that the keys are higher up. Also definitely try to take advantage of this ability when avoiding the evil shadow figure we talked about earlier. Although it mimics your every move, doing a couple of slick moves can help you gain some separation from it.
After a While, The Shadow May Disappear
An interesting (and possibly helpful) thing about Shadow Frog is that the thing in the game's namesake that's chasing you doesn't always stick around. After dying a few times, the shadow may leave, so this gives you one less major hazard to worry about.
Some of the levels already have plenty of spikes to worry about. Heck, you even have bouncy platforms that can lead to spikes up above if you aren't careful. Keep in mind, I'm not saying to die on purpose. Having the shadow there is a great way to challenge yourself, so if you can beat the level and avoid it as well as the other hazards, then go for it, legend.
Just keep in mind that, if you're really struggling, you can breathe a bit easier once the shadow leaves your sights. You'll have the freedom (sort of) to go for the keys. Just, of course, make sure to watch out for any spikes and other hazards that get in your way, and then you're home free.