Hello and welcome to the RM2 family Ciderman.
Some good points about RM2 were made and it's those points that set RM2 worlds apart from other gaming systems.
RM2...
- level 1 PC's are weak, adolescent type, pubescent even as they've not yet reached their "potential" stats, only their "temporary" ones.
- is definitely grittier than other games and IMO, more realistic
- you don't tend to die from HP loss, you die from Crits. I've had a player bleed to death from an 'E-Tiny' crit and it was the funniest thing ever!!! I had another PC kill my Orc Captain in the 1st round of battle with the very first hit. "E-Slash Crit" severed artery in leg, breaks bone, foes dies.... GM sighs in disbelief.
Hurin said it best, it seems like you are doing everything right. There are some minor things to consider for the scenario you play tested:
1) While you chose level 1 rats, you chose TEN of them. It was 10 vs. 2 or at best 5 vs. 1, or (6 vs. 1 and 4 vs. 1 if you used the optional pack-attack). Those aren't very comforting odds, even with level 5 PC's, 5v1 is daunting.
2) Spell casters are very weak early on in RM2 but get very powerful. The fighter needs to protect the spellcaster while she preps, then casts the spell. In your scenario.... 10 rats vs. 1 fighter while a spell caster preps a spell. (3 rounds.... 2 for prep, one to cast)
3) Spellcasters are not fighters, as evidenced by the 16OB. At PC creation, you get "Level 0" and "Level 1", that's two levels of development. In another thread, it was shown that a level 1 spell caster could have access to four known lists. Difficult to be sure, but doable.
4) Rats hate fire..... just saying LOL Drop some oil and make a spark.
5) Have you ever tried to catch a field mouse in real life? I've tried, but damn it all, never been able to! Never mind being attack by 10 of them!
You had the right idea for play testing, using a spell caster and a fighter to get a good feel for the game. You gave a nice small group, level 1 creatures. Try the same PC's again, but send them against 2-3 goblins instead. Don't change any stats at all or rework the skills. Just drop the same two PC's against a different type of creature and see what happens. I bet they'll do much better and you'll get a good comparison for the types of creatures and NPC's to use for your upcoming gaming session.