Returnal is a rogue-lite, with my areas to explore and upgrades to find. But of course, it isn't that simple. Bosses are impeding your way between the different biomes, and these must be defeated to progress.
In Returnal, you will fight five bosses in total over the six biomes. The only biome that you will not encounter a boss is the Fractured Wastes. The other five biomes, the boss, must be killed.
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Each of these bosses will be harder than the last and will test you in what you've learned throughout your time with Returnal. Have you learned to dodge bullets and lasers?
Do you have to fight the Bosses more than once?
Once you have killed a boss, you do not need to kill it again if you die. All bosses stay beaten, so you can bypass them on new runs, which will speed up progress.
But if you wish, you can challenge any boss as many times as you want. This can be done by heading back to where you fought it or finding a red door located on your map.