Gunhouse
I started playing Gunhouse in February 2019 as it was provided in the PlayStation Plus games package for that month. It was originally released on the PlayStation Mobile platform in 2014.I've been playing this game for way too long (5 months, mostly during my work commute when I feel like it). I've decided to document my datapoint for reference, in the chance that someone else out there has been too. This means that most of the following will make sense to very few.
Day 300
Game progression is split into days where each day is split into three levels. My estimate is that 30 days is more than enough for most people. The highest trophy/achievement requires 100 days, which is a slog. I just kept going till day 300 and onwards because I had my 'system' and executing it felt like going into a flow state.I think the game gets progressively harder, either way I'm not at the point where the game is hard yet; completing each level is still a formality, even if I die here and there out of carelessness.

Hardcore
"Hardcore" mode is a typical survival mode where you start off at the beginning, levels get progressively harder and you keep going until you die.Reaching Day 8 is probably good. The hi-scores shows I reached Day 8 on my second attempt, I didn't want to make further attempts in case I didn't do any better and make it look like I took multiple attempts instead. Which is funny because as if anyone cares!

Blocks Loaded
A full house of 3x6 is what I try to go for most of the time.
Weapons
Here's the trio of weapons that I feel most comfortable using, in order of most important first:- Sine Wave (Special) - Temporarily freezes all enemies; for this duration you can have your way with the enemies. You could probably survive with this weapon alone but it would take a while as it doesn't do much damage.
- Beach Ball (Gun) - These are very powerful and linger for a good while on-screen. The lingering helps deliver even more damage but also gives enemies time to move forward, which is why I only use it when enemies are frozen with the Sine Wave special. Using this as a powered-up full-screen attack (all guns at once) annihilates everything, so that's what I do.
- Dragon (Gun) - Meh, I'd rather have more beach balls instead. However this does a lot of damage in little time, the "little time" being important as you don't have to care about freezing them. But another weapon may well be better choice.
My "Favorite Gun" switches between those three weapons:

The Good
There's plenty more good than what I'm listing here, but it's what pops out in my mind:
- The weapons are varied and interesting. If a lot of thought went into designing these weapons, it really shows.
- You can sell weapons for as much money as you bought them, it took me a while to realise this! There's no refund-tax which means you could enjoy experimenting with any weapon.
- The game is a little weird, humorous and doesn't take itself seriously, which works for this title.
"I've been playing this too long"
Here are some amusing oddities that occur when you've played this game for probably much longer than it was designed:
- In my flurry of swiping, quite often I'll get "lucky" and inadvertently create a big block and swipe it off, overwriting some powerful guns I was saving up to be replaced by a puny weapon that I didn't want. After being burned by this too many times, I've now learned to build my blocks such that I have to swipe in the direction away from the guns/specials that I'm building up. Still, every now and again I'll get bitten by this and I'll yelp (in public)!
- After reaching Day 200, I found that when the game refreshes any objectives you've cleared (after completing a level) the game intermittently crashes. It's no biggie since the levels are easy to re-do and sometimes quitting to the Shop before the refresh happens helps.
- Sometimes the 3 "current random objectives" get stuck to the same "Upgrade healing to Level XXX" which costs more money than you have, so you can't clear them for a long while.
- It would have been nice if the balance display accommodated a few more digits... :)