Wonderboy in Monster Land 1CC (Arcade/X360)

Recorded via the excellent X360 port by M2 (Sega Vintage Collection: Monster World)
A strange game for its style.
It's not an "easy" game per se, but the challenges probably aren't what you'd immediately expect. Many places taking a hit doesn't matter at all, while certain mistakes can be completely detrimental to your run.
The most important part of beating Monster Land is routing the game to make sure you get all the equipment you need, with the legendary armor and sword being top priority. Each run can also be very prone to pure luck, so ideally you also need your strategy planned out to mitigate bad luck as much a possible.
I actually make a mistake, accidentally buying the knight armor instead of the heavy armor, which means I needed to buy one additional armor to get access to the best one. On this run though, I had more than enough money to manage with little issue.