For the people saying Gungeon is like Isaac with guns...I'm going to strongly disagree.
On the surface it may look like it. However, Isaac is more about strategizing from the items available to build the most powerful run possible. You have to maintain in your head how active/passive items and consumables all intermingle to craft a unique experience every time.
Gungeon isn't really like this. In Isaac, you essentially have one weapon that you modify in a startling number of ways. Gungeon you pick up weapons, most of which aren't that great, and you have very few synergies. The moment to moment gameplay in Gungeon does feel tighter to me, but it's also more difficult than Isaac. For me personally, these differences soured gungeon, along with some of the sparse ammo problems and the longer floors than Isaac. I am still probably going to pick it up for the Switch, especially because I'm hoping the Gungeon & Dragun update fixes a lot of my complaints.