Yeaaaah balancing in the demo is a thing. The demo is weirdly enough harder than a lot of the actual parts of prototype, which is why you may have seen a few high ranking profiles saying how they beat the demo under their "achievements" sector.
-- Ender's guide on how to "beat" the demo whooaaaaa --
-Part 1: Met Hyper Bomb twice. Boom (hah) you did it.
-Part 2: Cut and Metal Spam Dive Missile for Metal, and Super Throw and charge shots for Cut. Alt strategy: Mega Slide and Mega Ball to win!
-Part 3: aw jeez this one sucks (Orb City) >Crash is weak to Wind and Shield, so the strategy for him is to switch to Proto and spam Skulls. Crash Bomber is a instant KO, so take him out as fast as possible. >>Alt strategy: Proto Strike, then buster shot. >Wood Man is weak to Cutter and Flame, so, first, use Bass Crush to weaken his tanky defenses. He is going to immediately use Leaf Shield, so charge the Bass Buster. Then, use the Bass Buster or Quick Boomerang, though the BB has more accuracy. May want to raise a Leaf Shield yourself to increase your defenses for a while. tl;dr wood man sucks >Ice Man: PROTO STRIKE >Bomb Man: PROTO. STRIKE (hope you get lucky with a crit hit as well!)
-Part 4: AAAAAAAAAAAAAAAAAAAAAAAAAAAA (Oil Wells dot jpeg) >okay so where to begin >This level is a 3v6 battle that is nearly impossible. No joke. This is harder than almost every single battle in non-demo Prototype. To say this is even remotely fair is a complete blatant lie. Use Proto Strike and Bass Crush wisely and you may get out alive. Pray to whatever gods you may believe in that you get lucky with critical hits, and not the enemy (especially if the enemy if Oil or Elec. Those dudes are complete beasts. Once again, good heckin' luck, boy. >may. :^) >Some useful things to remember while attempting this beast >Mega Buster always gives a defense boost, so may want to always have it charging while using other attacks as Mega. >Fire Storm right away on Oil. >Use Proto Shield! It is reaaaally useful, believe it or not! >DON'T FORGET YOU HAVE ITEMS!!! >Earth Blitz on Elec Man. Proto has a resistance to Electric and Earth Blitz, in combo with the 1.5 power of the field, and if all three drills hit, can be DEVASTATING. >Wood Man, like last time, is garbage. Use bass once more, in combo with Proto Shield, Bass Crush, and Leaf Shield. >PRAY that the Robot Masters don't EVER switch. Or if they do its Wood ==> Bubble >Never, I repeat EVER put down Leaf Shield as Bass. That 40% defense increase saved me, man. >while making this guide I only had bubble left, and died. reminder to use your heckin' items, boy, because now I have to do the worst thing ever again in the hopes of trying to beat this horrible demo. >Use the buster shot to save Weapon Energy where you can. >Kill Heat Man as fast as possible. His atomic fire attack boosts really get stupid powerful. >Don't switch to Bass while Fire is up. Bass has a fire weakness. Bleh. >Don't let any your robots die before beating the second robot, usually Fire Man. >Mega Slide has priority, like Quick Attack in pokemon. >Bubble barely does any major damage, but you should still try to quickly get him out as he can be problematic because of his aimming powers with Bubble Lead. Pray he uses Bubble Spray more. >Bright Burst lowers defenses, so you can use that to your advantage against the more tanky boys (mostly Wood and Heat) >For some reason, you items don't come back. Why? I have no idea. This is very very very dumb, especially with how there is no demo shop. >Don't forget that in the in-battle menu, you can charge your weapons for the cost of leaving your self open. This really helps a ton, believe it or not. I think that abooout covers all you should know while doing this garbage mission. Once again, good luck, you will need it.
Not being able to do any sort of level grinding or be able to get other robot masters is just So. Dumb. I could go on a complete tangent on how the demo being too hard thus could have potentially driven away new players from trying normal prototype, as the demo just... sucks. Something that is a short segment of the actual game shouldn't be this hard, especially with how apparently there is the only actual way to fight Quint outside of Bonus Field II is Level 5 or so in the demo. Yes, that is right, a secret superboss is hidden away in the demo. Again, or so have I heard. I have never made it past Oil Fields, so I don't know if this rumor is true or not, but if it is, then uuuuuugh why. If you ever do try to beat the demo again though, once again, follow my bad guide, and use items, but only when you really need to. If you make it to whatever Demo Level 5 is, then do tell what is in it and what not. You probably won't because of how Oil Fields is harder than most high ranking player battles but hey good luck none the less, right?