Great job- Takes patience.
This will probably get flagged as useless by some spit-hole, jeb-end.
The game is definitely a challenge. I found the whole thing to be well made and offer an interesting challenge. I have to agree with some others, it can be very difficult and thus frustrating. The time it takes for money to multiply EVEN with 3 salvages looks the same as with 1. I only got to the 2nd level and decided that after being at work all day this game just bothered me, so I decided against pursuing any longer than 20mins.
Great concept and game but ridiculous at times. I enjoy a challenge but my state of mind just didn't allow for patience or devising a strategy.
Even if you wait to drop shovels in waves you are fucked by constant horde on level 2 so the time it takes to garner more salvage is just about impossible.
After writing this I might give it another go. Word of advice- try to get as many salvage as you can before the jumpers & screaming psychos and the fatman come! The common horde can be culled often with a healthy amount of shovelmen.