Simplified spellcasting

Despite the game's overall simplicity, the spell memorization and casting rules of classic D&D have always seemed overly complicated and cumbersome. I get the rationale behind it. Just like choosing which supplies and equipment to carry on a given expedition, it adds an element of planning and resource management to magic which you wouldn't get in a system that allows free-casting from among all the spells a character knows. I just don't think it does it very effectively. It's a lot of referring to charts and tables and lists, a lot of extra bookkeeping for the player, and in my own experience encourages players to default to load up on multiples of a few high-powered combat spells and avoid other potentially useful spells.

What I'm looking at is essentially a spell-point system, but one that utilizes minimal math and dead simple tracking that eliminates the need to refer to charts and tables, while retaining an element of resource preparation and management.

A magic-user maintains a spell book with all spells known, but can only memorize one spell level per level of experience, plus or minus the Intelligence modifier (minimum of 1 spell level in the event of Int penalties.) Thus, a 4th-level magic-user with Intelligence 14 (+1 bonus) could memorize five spell levels, in any combination the player desires. That could be five 1st level spells, two 1st and one 3rd level, one 1st and one 4th level, or any combination that adds to five.

A magic-user has two spell points per level of experience per day, which can be used to cast any memorized spell as often as desired, so long as the caster has enough spell points remaining. A full night's rest will restore all spell points, and lesser rest periods might restore them partially. Our level 4 MU from above would have eight spell points per day.

This ends up giving low-level magic-users a little bit of a power-up, and high level ones significantly less total firepower, as you can see in the table below:

Character Level	Standard Total Spells	Standard Total Spell Levels	Revised Total Spell Levels
1	1	1	2
2	2	2	4
3	3	4	6
4	4	6	8
5	5	9	10
6	6	12	12
7	8	17	14
8	10	23	16
9	12	31	18
10	14	40	20
11	16	47	22
12	19	60	24
13	21	69	26
14	22	73	28

This might seem unfair to higher-level characters, but I think the gains in versatility compensate for the loss of total power. How many of those extra spell levels are destined to go uncast because they're tied up in spells that weren't useful for situations faced in that day's adventure? In the standard system, if a player wants to be able to cast plenty of fireball spells, it comes only at the expense of the ability to cast other spells, especially of the niche and utility variety. In the revised system, the player can choose a single instance of fireball and a few utility spells too. If the latter prove useful, the character has access to them, and if not, the power can be channeled into extra fireballs with none going to waste.

You might also notice that a caster won't necessarily be able to memorize a spell of every level he or she can cast. Again, I think the ability to use every last spell point through the versatility of limited free-casting plus the ability to memorize any combination of spells (e.g. a  high-level caster could choose all 1st and 2nd-level spells if desired, or a mid-level mage could forgo low-level spells completely in order to take a single 6th-level spell, is sufficient compensation. It's an interesting resource management choice, while limiting the sheer bulk of decisions to make when selecting spells to memorize.

Bottom line, if you know your character's level and the levels of spells, you know exactly how many spell levels he or she can memorize and cast without consulting a chart, and within those limits you have carte blanche. If you can add and subtract single-digit numbers, the on-the-fly bookkeeping is a breeze. You don't have to keep track of which specific spells you've cast; it's literally as easy as tracking hit points.

A few consequences of this system that I think could prove fun, useful, and/or interesting:

• It makes the Intelligence adjustment relevant in ways other than XP bonuses, without making an 18 Intelligence virtually mandatory. A magic-user gains (or loses) a little versatility based on Int, but not overall firepower. 
• It allows for partial restoration of spell points, such as through less than a full night's rest or magic items such as potions that restore a point or three.
• It allows for magic items that aid in casting, such as a wand that reduces the casting cost of a particular spell or category of spells (fire, charm, detection, etc.) by a point, or a hat that allows an extra spell level to be memorized.
• You could easily add a rule for casting beyond one's ability using hit points (1d4 damage/spell level, cannot be restored magically but only by rest?) after the character's spell points are expended, and/or a rule for casting non-memorized spells from a spell book at a greater spell point cost. 
• The linear warrior/quadratic wizard conundrum is somewhat mitigated. 

This is what I'm going to use for my Goblins & Greatswords fantasy heartbreaker, but it seems that it should transplant pretty well into any old school edition of D&D without too much fuss.