OK, having played it for a bit, and I loving it so far. Here are some things I think would improve the game:
-Like it has been said before, the main character needs some recovery time after being hit by an enemy. As it is now, physical attacks are useless, and as soon as enemies gang up on you you are pretty much dead, there's no way to get out.
-As it has been pointed out, being able to "see" a cone of vision, or the extend of the enemy sight would be awesome.
-When you die and respawn, the enemies that were looking for you should be gone. Sometimes I die near (or in) a respawn point only to be killed again by the same mob that killed me before.
-Mines are too cumbersome to use. The fight against the tank becomes needlesly complicated because of this, as you have to lift a hand to reach the mine usage key. Maybe you could have a "use item in x slot" mechanic? Just like you can equip different wepons and then hit fire, you could be able to equip a type of explosive then use it.
-Sometimes the game tries to be too modern for it's own good. Why do I have to press a key to pick up an item? I should be able to just walk over it to pick it up.
-The box doesn't seem to be doing much. Sometimes it just unequips by itself
-How come I can't use my cigarretes to detect laser beams?
-There should be a hotkey to get to the radio when called.
-Dogs don't show up in the radar.
-Is the jump any use?
-Why isn't the TNT just pastic explosive? It makes more sense, militarywise.
-It would be great to just type the passwords instead of using the mouse.
-Why can't I keep my rations equipped to avoid being killed that easily?
-Controller support would allow for different analog movement speeds
I hope these suggestions are useful for you

Thanks for your suggestion. Will keep in mind for sure.

 A few things:

The carboard box works just fine. It unequips after 8 seconds on purpose. This is to avoid spamming. It says in the description "It might be a little claustrophobic in there"

Dogs do show on radar. I just tested it to confirm.

Cigs didn't detect laser beams in the original. So they don't here either. Use the infa red goggles. That's what they are for. Otherwise they would be a useless item.

Jump is used to jump over the roller traps. Use it only if you want to.

I just changed the password menu from using the keyboard to a virtual one in the last update. After testing with it for the last year and a half, the new virtual keyboard is MUCH better!

Rations work the same as the original.

I changed from plastic explosives to TNT for sound and visual effects.

The hotkey for the radio is TAB, it opens the backpack to get access like the original. (I'm trying to keep some things classic)

Thanks for reaching out with some suggestions. Much appreciated!