level 1 : .45 Colt – Upgrade Strength + Clip
level 2 : .45 Colt – Upgrade Clip
level 3 : .45 Colt – Upgrade Reload
level 4 : .45 Colt – Upgrade Strength
level 5 : .45 Colt – Upgrade Reloadlevel 6 .45 Colt – Upgrade Strength
level 7 : .45 Colt – Upgrade Clip + Reload
level 8 : Save cash
level 9 : Save cash
level 10 : Buy Tec-9
level 11 : Buy Builder
level 12 : Tec9 – Upgrade Strength x2
level 13 : Tec9 – Upgrade Clip + Reload + Buy Ammo
level 14 : Tec9 – Upgrade Clip + Reload + Buy Ammo
level 15 : Tec9 – Upgrade Strength + Buy Ammo
level 16 : Tec9 – Upgrade Clip + Buy Ammo
level 17 : Buy Scavenger Tec9 – Upgrade Reload + Buy Ammo
level 18 : Buy Assistant Tec9 – Buy Ammo
level 19 : Tec9 – Buy Ammo
level 20 : Upgrade Scavenger Tec9 – Buy Ammo
level 21 : Upgrade Scavenger Buy Rage , Buy Tec9 Ammo
level 22 : Save cash
level 23 : Upgrade Scavenger Buy Tec9 Ammo
level 24 : Save cash
level 25 : Buy Tec9 Ammo
level 26 : Upgrade Scavenger [MAX]
level 27 : Upgrade Builder Buy Tec9 Ammo
level 28 : Upgrade Assistant
level 29 : Buy Tec9 Ammo
level 30 : Upgrade Assistant Buy Tec9 Ammo
level 31 : Fortify Pub x2 Buy Tec9 Ammo
level 32 : Save cash
level 33 : Save cash
level 34 : Buy Tec9 Ammo
level 35 : Buy Tec9 Ammo
level 36 : Save cash
level 37 : Save cash
level 38 : Save cash
level 39 : Buy Tec9 Ammo
level 40 : Buy Mini Gun + Upgrade Strength + Buy MiniGun Ammo
level 41 : Save cash
level 42 : MiniGun Upgrade Strength
level 43 : MiniGun Upgrade Strength
level 44 : Save cash
level 45 : Upgrade Assistant + Buy MiniGun Ammo
level 46 : Upgrade Assistant + Buy MiniGun Ammo
level 47 : Upgrade Builders
level 48 : Upgrade Builders + Upgrade Assistant [MAX]
level 49 : Upgrade Fortify Pub x2 , Buy MiniGun Ammo
level 50 : Upgrade Fortify Pub [MAX] + Buy AIDS + Buy Myxo
level 51 : Upgrade Builders [MAX] + Upgrade AIDS X2
level 52 : Upgrade AIDS x2 [MAX] + Upgrade Myxo
level 53 : Buy 20 Grenades + Upgrade RAGE x 3 and now you will be good

There are many was to beat the game its not that hard, but here is just one way.