One of my players commented about damage to weapons in Felltower and simplicity.
What it comes down to is that just because some things are simplified it doesn't mean all things are simplified.
One, if not the, central idea of Dungeon Fantasy is killing and looting. in Felltower, that's magnified. You can describe the game like this:
PCs will face challenges centered on exploring hostile areas, attempting to deal with the inhabitants by any means, and find a way to gain loot from those areas. A core of the challenge will be combat and gaining and extracting loot.
In other words, things that make combat more entertaining and/or challenging, and which improve the experience of "explore the area" and put a challenge around getting loot are central. Other things are peripheral. "How to defeat the enemy?" and "How to get the most value from the loot?" are critical questions and challenges to players' cleverness and problem-solving. Success and/or failure at these tasks affects character XP and the availability of things in the environment.
We don't handwave away the problems of burning loot up with Fireball spells or the encumbrance of that valuable but big and bulky statue. We may abstract the conversion of value or die-roll damage, but it's not removed from the game because it's still related to the core activities.
What is simplified in DF Felltower?
We simplify and abstract a lot in DF Felltower - often beyond what Dungeon Fantasy does. I play with a sub-set of the sub-set of rules.
We abstract town even beyond that in DF2. Jobs are just assumed in downtime, and offset cost of living. Hirelings are rolled for. Rumors, rolled for. NPC interactions in town are just descriptions of what happened thanks to your die rolls (mostly.)
We abstract out the world to the point where my maps are good enough. We simply put aside things that don't directly impinge on our gameplay. The world responds to the players, not the other way around - a bad roll for finding hirelings might be explained by, "Huh, must be a war on somewhere, everyone's working."
Religion is a monotheistic church of the Good God and it's based on the Good Book.
Economics is based entirely on the success of the PCs in looting the dungeon and spending money. Coins are worth their face value unless they're some kind of unusual treasure. We don't worry about coin conversion and debased coinage and so on, or the effect of a lot of cash on the local economy except as it makes more cool stuff available to PCs.
Basically, if it's outside of the dungeon and doesn't concern the challenge of extracting loot from the dungeon or exploring the dungeon or killing monsters, expect it to be simplified or abstracted.
What isn't simplified in DF Felltower?
Just because we simplify some things in DF Felltower doesn't mean we simplify or abstract everything.
In some areas, we expand the options. We use Committed Attack and Defensive Attack, Beats, Ruses, parrying improvements for some two-handed weapons, Feint defense based on your best weapon skill (not the current only), and Quick-Readying weapons from the floor - all from GURPS Martial Arts. None of those are assumed in DF, we added them. We don't add more, and we do use more basic versions of other rules, where the added time from the complexity is seen as taking away from the "exploring" and "looting" part of the triumvirate of awesome and putting it all on the "killing" part.
In others, we leave the details as-is because that's part of the campaign.
Encumbrance? Actually, this is already simple, because we use real-world weights and measures.
Damage to gear and loot? Abstracted a little, but part of the challenge. You can't split skulls and then loot helmets. You can't melt the enemy in a vast pit of fire and then take their gold necklaces off of them. You can't provoke the acid-spitting dragon or grapple the rust monster or dance with the disenchanter and expect that your stuff will be fine.
Mapping? We make this a little easier than it realistically should be, but otherwise leave it as-is and make the PCs do it. "Explore the dungeon" is a critical gameplay element, so this stays fiddly.
Ammunition? Consumables and supplies? These are all part of the challenge of go, explore, kill, loot, and come back. They're tracked to the arrow, the meal, the torch.
Time in the dungeon? Tracked to the minute when it matters (or by the 4-hour block, outside.) Time is a consumable, and comes with costs in Wandering Monsters and resource usages and resource regain.
It's all centered on the main parts of the campaign. Your sword might break, the gems might crack under the heat, the barbarian might smash the valuable antique helmet. You might get so much loot you can't carry it out, or take so many casualties you can't carry them out. Equally, you don't worry about getting robbed in town, or where you keep your backup magic sword in town, or why there is a shop in town that has rations, paut, and healing potions. The peripheral stays so, the central stays so. We may modify the specifics based on actual play but the core stays the core.
DF Felltower may be simplified, but only where it needs to be.