There are way too many reviews for this game spouting cheap, repetitive, barely-descriptive one-liners like “Link to the Past meets Roguelikes!!! A+ very good game!!!” or “Homage to old dungeon crawlers” when the fact of the matter is that it’s just not a very good game. The best thing it does is work without crashing.
The weapons given to the player character are a cannon launcher and a sword. These deal unimpressive amounts of damage even with upgrades. There are also perks that the player can pick up a-la Binding of Isaac for abilities. Unlike BoI, however, these perks don’t really change the way that the game is played too much since they either allow the player to avoid hazards or tack on slight effects to the two weapons (e.g., cannonball explosions spawning tiny pools of fire). The player can upgrade their treasure chest companion by collecting gems to the point where it will fire spikes at enemies or dash around into enemies but those are the only other attack that can be performed.
There are a lot of different sprites for enemy types but they all follow the same pattern: +forward. Everything either runs towards or away from the player, including bosses. This, in combination with the weapons, makes combat really boring and shallow. The gameplay doesn’t particularly change much outside of the included minigame, which is essentially Pac-Man. Click to slash, click to shoot. There’s nothing like BoI’s bullet-hell, active abilities, or item synergy. There’s nothing like Ziggurat’s arena shooter approach to survival (good movement, good positioning, good aim). There’s nothing like Dungeon Crawl Stone Soup/Tales of Maj’Eyal/Nethack/others where items and random events legitimately change the player’s experience (e.g., Bearosphere in ToME). In essence, it’s LoZ: A Link to the Past without anything that made LTTP good fused with the permadeath behind Roguelikes.
The art design is explicitly stated as a “nostalgic 16-bit look and feel” but there’s so much dark and grey and brown, any attempt to have anything that looks at the very least different is crushed. Hammerwatch tackles “retro” in a far superior graphical manner, and Darkest Dungeon utilize black, brown, and grey to create a foreboding atmosphere. Diehard Dungeon just looks like a flash game. There is also a lot of screen clutter in Diehard Dungeon; broken barrels and boxes covering up progression items (keys), tiny shelled critters running around everywhere that don’t deal damage, bouncing spinning spikewheels, etc, all in a small room. Others might say that "this just helps cover up traps!!!" but the fact that it's really easy to see where the physical traps themselves are (spike walls, arrow holes, etc.) defeats the purpose of hiding the trigger.
The XP system and ability system are completely useless. The only thing gaining XP does is increase the difficulty of the mobs and doesn’t change anything about the player. No power bonus, no extra abilities, nothing. All abilities are acquired via RNG chests where players play slot machines for random abilities, which determine the player’s pace; if the abilities picked up are useful, the player can actually play the game at a reasonable pace. If the abilities are garbage, players are forced to plink away at enemies until the odds roll in their favor. Another reviewer described the game as “tedious” and I can’t help but agree; it’s not a fun
timesink, it’s not a game one can leave running in the background like a clicker game, but it requires the player’s undivided attention to open the exit to the current room. It feels familiar but unlike the claims, it does nothing unique or out of the ordinary.
It’s fitting that Diehard Dungeon was released on Steam on September 11th because this game is a disaster. Spend your $5 (or $0.99 if on sale) somewhere else.