Sidescrolling simplifies the code, but look at what Extrude said. Just about everything he mentioned still goes, as with everything I've brought up.
It's a relief sidescrolling simplifies. And
1.Some system for terrain generation / block placement
2.A way to keep track of which treasure is in which chest
3.You'll need more if you have boss battles / multi-piece enemies.
1. What? Why? The map stays the same.
2. Most items are only obtained by bosses. Others are found lying around here an there like the Stoenwahl equipment.
3. Like I said, it's going to be sidescrolling boss battles, so that simplifies it as Mega said.