Money is more valuable than abilities. Always repair units before selling them. And don't be too stingy about using your other three resources: Losing a unit will likely set you back too far to complete Directness (and it helps you get Efficiency Gold, if you're after that).

Supply units aren't all they're cracked up to be. See Troops.

Blasters are distractions that keep your units from collecting Carusarum and, more dangerously, from firing on more important objectives. A fully upgraded Crawler takes these down with one shot before they have a chance to return fire. However, given the slow retargeting speed of Crawlers, an airstrike that takes out a pair of Blasters near, say, a Behemoth can be more effective than airstriking the Behemoth itself.

Scorchers aren't as dangerous as they seem. They always target (and only damage) the farthest unit in range, so if you're facing them head-on, be ready to shuffle your convoy to move damaged units to the front. Smokescreens are very useful, as the damaging edge of the plasma blast ends up randomly moving forward and back, dealing sporadic damage to your group (instead of focused damage on one unit).

Behemoths are slow-turning, so judicious use of the Commander (to initially turn the Behemoth away from the convoy path) and a decoy (to again move the tower away from your units once it has detected them and turned back) should give enough time to eliminate it. Smokescreens can help your decoys last longer, but risk letting the Behemoth get lucky area shots near your convoy. Once you get a fully-upgraded and shielded Crawler, you might find you don't need to decoy lone Behemoths at all.

Stormrays kill shields but aren't so devastating against armor. They are easily taken down with two normal Tanks--don't even bother shielding them. Follow those Tanks with Crawlers, and the latter should barely be touched, as two Tanks will soak up the primary and secondary damage. Just repair the Tanks and don't smokescreen so as not to put the rest of your convoy at risk of random zapping.

Hackers are arguably the most difficult towers to handle. They have a ridiculous range and take two airstrikes to eliminate. They are subject to decoys, but only if they are within the radius of the effect. Sure, you can run the Commander off the path to lure one hack away, but then your convoy is vulnerable (I lost count of how many runs I lost this way).

Your best bet might be to keep a couple of Tanks/Dragons in front (as with Stormrays). They have a short range, don't damage the Commander as quickly, and it's probably not fatal that they're shooting at you instead of towers for the couple of seconds it takes you to run in and repair/smokescreen/decoy.

Energizers' worst effect in a Directness run is that they reduce the radius of your powerups. Since you're running for the exit most of the time--Wave 18 excepted--it actually doesn't matter as much that towers might respawn behind you... you're not going back. Still, airstrike them if you can (bonus points for damaging adjacent towers, but that's risky as Energizers shrink the blast radius).

APCs are good damage soakers in a pinch, but other than the first few seconds of Wave 1 (to take out a Blaster or two and harvest some Carusarum) I did not use them.

Crawlers do good damage and should always be part of your convoy. Even when facing high-damaging towers, it's worth letting an upgraded Crawler take the first shot before reshuffling it behind Tanks. A Level 3 Crawler is an important milestone to reach; however, three unshielded Level 1-2 Crawlers do the job on earlier waves. (Don't be too quick to switch a damaged Crawler with one farther back in the queue--you may find that it's no longer firing because it's now pointing in the wrong direction and has to slowly swivel back. Plus, it's nice to have an undamaged unit to sell for upgrades or a Tank.)

Shields should be deferred until you're sure you can do enough damage to the towers you're rushing by to destroy them. They're not any good against Stormrays anyway and keep trailing units out of the fight longer, meaning Behemoths get that extra shot off. (Conversely, they can be another, minor source of armor in front of your Crawlers against Stormrays.)

Tanks are great against Stormrays and it's worth selling all but one Crawler to buy a couple on waves that include that tower type. Remember that repair heals units by percentage of total HP, so repairing Tanks, Dragons, and APCs is comparatively 'cheap'.

A Dragon is probably best used when you need to attack both an objective and defending towers. That pretty much means Wave 18.

Supply units sound like a good idea. However, more firepower means more towers killed, and in Tokyo Raid (and Baghdad Mayhem, for that matter), most towers drop something. There's nothing worse than leaving a Behemoth behind with a sliver of life left... and probably hiding a decoy or airstrike. During my successful run, powerups were not a limiting factor. While I didn't kill as many towers and collect as many powerups as in Ruthlessness, I likewise didn't face as many towers that required I spend resources, either. (During several unsuccessful runs, I had to constantly use repair to keep Supply units alive... and they died anyway, taking their cash value with them.)

The following describes my first successful run, with lessons learned along the way.

In italics after each heading is the squad I started the Wave with, or upgraded to very soon after Wave start. Asterisks (*) indicate upgraded unit levels.

Buy 2 APCs

Upgrade to 2 Crawlers as soon as reasonably possible. Remember, though, that APCs collect Carusarum very quickly and can handle solo Blasters well enough.

If the direct path doesn't include two pairs of Carusarum caches, reload. If you end the wave with less than two Crawlers and $80, reload. The best I have amassed here is two Crawlers and $100, and that's using an airstrike. (Using up one of your two starting airstrikes is not a terrible idea. Not so much because killing a pair of Blasters gives you $10, but it can free up your units to shoot Carusarum.)

2 Crawlers

Get a third Crawler as soon as possible. Multiple Crawlers are superior to upgrading when it comes to whittling down big towers at this stage.

You don't want to have to loop around to finish off Behemoths and Scorchers, so be prepared to lay down smokescreens and decoys, and as a last resort call down airstrikes to weaken or finish off objectives and eliminate distracting Blasters.

(I gambled Directness here: I made direct paths to each tower, with my last objective the one closest to the exit, meaning the convoy passed the exit after killing the Behemoth and had to loop back once. That allowed for some additional targets to be killed.)

Don't be like me--remember to set your path as directly to the exit as you can after you get the objective complete message. On at least two attempts, I was caught admiring my units as they blissfully ran past the bridge.

3 Crawlers

Make your direct path and run to the exit. If you're lucky, you can take a couple of Behemoths out on the way for more resources and use an APC to collect any Carusarum caches while your Crawlers are busy with farther targets.

4 Crawlers

Once I collected a bit more cash here, I was able to sell a Crawler and upgrade two. I did have to make one last loop at the end of the direct path, which I hope didn't penalize me too much. I used an airstrike to finish off a Behemoth and Blaster--a fair trade for more cash and a pair of lesser powerups.

2 Crawlers* + 1 Crawler
The first and most important powerup grab. The direct path does not allow a lot of time (40 seconds, in fact) for gathering. At best, you'll be able to clear out one side and maybe pick up a middle area powerup or two on the way. Use an airstrike on some blocking cars if it leads to a cache with another airstrike to replace it.

On this run, I actually used two airstrikes as the left side groups included 5 airstrikes in total.

2 Tanks + 1 Crawler**

Stormrays. Repair and sell enough Crawlers to purchase two Tanks. (You might hold off if there is an easy Blaster or two within Crawler range on the way in.)

Set a path to circle the inside of the Stormrays and let your Tanks (and any trailing Crawlers) take them out. Repair as needed. Behemoths on the outer ring shouldn't cause any trouble. In fact, you can probably kill one as a bonus on your way out.

1 Crawler** + 2 Crawlers*

Escort mission. Take the exit with the shortest possible path. With no Stormrays around, sell the Tanks in favour of Crawlers.

2 Tanks + 1 Shield + 1 Crawler**

Stormrays and Behemoths and Scorchers, oh my. Time to bring back the Tanks and put the rest into a high-damage unit. I'm not sure the Shield helped all that much. I ended up selling it to get another Crawler to help take out some big towers.

1 Crawler*** + 1 Crawler*

Clear the path mission. No Stormrays, so Tanks were sold to acquire my first fully-upgraded Crawler. I was able to buy a Shield (again) early in this wave to provide some protection and used an airstrike to eliminate two Blaster objectives off the direct path.

2 Tanks + 1 Crawler***

Other than an initial Blaster, the only towers in my way were Stormrays. However, they are widely separated on this island and their range is a problem--I often found myself in a crossfire--so don't wait to repair. I ran for the exit, hitting a pair of patches of Carusarum (4 total) on the way. Lucky, old man.

1 Tank* + 1 Tank + 1 Shield + 1 Crawler***

Hackers and Stormrays. In general, I'm less concerned about Hackers with Tanks in front. I repaired them when able and otherwise let the convoy take those towers out on their own.

2 Tanks* + 1 Shield* + 1 Crawler***

Escort mission. The Scorchers were more of a problem than the Stormrays in this wave because the Escort is often at risk at the end of the convoy. I used up a lot of repairs, smokescreens, and decoys here.

2 Tanks* + 1 Crawler*** + 1 Shield* + 1 Crawler*

The transport's path had Stormrays toward the front and a Hacker at the end. I used two airstrikes to kill one objective Stormray off the most direct convoy path. The Tanks took care of the other and were then repaired/sold to build up a second fully-upgraded Crawler for the rest of the wave.

1 Tank** + 1 Tank* + 1 Shield* + 1 Crawler***

Airstrike the Energizers. Tank the Stormrays. Consider airstriking the Hackers if off the path and/or near other towers.

Forgot to take note of my squad - see Wave 16 for what you should be able to afford at this point

Second, last, and least important supply run. Unlike my previous failed Directness attempts, I had upwards of 20 airstrikes and 40 repairs at this point (evidence that keeping Supply units alive ends up draining repairs in the long term). Decoys were getting low, though, so I picked the side that had more of those.

1 Dragon** + 1 Tank** + 1 Shield + 1 Crawler***

I used three airstrikes to eliminate the two Energizers and weaken a pair of Stormrays. I bought a Dragon, as the main corridor appeared to be flanked by towers. The Blasters were so easily dispatched by the Crawler, though, that I probably would have been better served by another Tank and Crawler. No Hackers, thankfully, so repairs were fairly straightforward. Another necessary but quick loop at the top of the map that didn't hurt Directness.

2 Tanks** + 1 Shield** + 1 Crawler***

Timed mission, so just run for the exit. In my case, four airstrikes took care of the three Energizers and weakened one Hacker/Stormray pair. I could have left all of them alone but I had airstrikes to spare--still 20+ going into Wave 18.

1 Tank** + 1 Dragon** + 1 Shield ** + 1 Crawler***

Need to loop through the generators (once each should do it with a Dragon) before taking on the center. I eliminated all the Energizers and Hackers with airstrikes, and then bombed the odd Behemoth and Stormray that had the misfortune of being placed next to squishy Blasters.
With the Hackers and Energizers gone, the final battle was a simple matter of repairing the Dragon and Tank as the Crawler followed them around the loop, dealing massive damage to the CPU. (Mercifully, the CPU does not regenerate Hackers or Energizers.)

I did lay down the occasional decoy outside the ring and a smokescreen on the path if we were getting beaten up and repair was on cooldown. However, I found the last stage less stressful than on my Ruthlessness run, as it was easier to manage the shorter convoy.

Medals: Directness Gold, Efficiency Gold