Learn Hardcore Japanese: atarasii sakusen nara kanarazu seikousuru to omoimasu. - With the new strategy, I think we will definitely succeed.

なら marks a conditional/topic: “if it’s (the case of) a new strategy / as for a new strategy.” It often implies contrast or selection from alternatives (new vs old). It’s based on an assumed or introduced condition rather than a time-sequenced “when X happens” type of if.

How is なら different from たら, と, and ば?

なら: condition based on a known or supposed situation; contrastive/topic-like. 新しい作戦なら… “If (as for) a new strategy…”
たら: temporal/real condition; “when/if X actually happens, then…” 会議が終わったら話します.
と: automatic result/every time; not for volitional outcomes. 春になると暖かくなる.
ば: more formal/hypothetical/neutral; often written. 早く出れば間に合う.

Who is the subject? Is it “we,” “the plan,” or something else?

It’s omitted and understood from context, which is normal in Japanese. It could mean “We will succeed if it’s a new strategy” or “A new strategy will succeed.” The ambiguity is resolved by the surrounding conversation.

What is the と in と思います doing?

It’s the quotation particle, functioning like “that” in English: “I think that ….” The clause before と is the content of the thought.

Why is it 成功する and not 成功します before と思います?

Subordinate clauses before と (the quoted content) use the plain form. You make the whole sentence polite by conjugating the main verb 思います, not the embedded verb. So 成功すると思います is correct; 成功しますと思います is not.

Why does 成功する (non-past) mean “will succeed” here?

Japanese non-past covers both present and future. Context and adverbs like 必ず push the reading to future prediction: “will definitely succeed.”

What nuance does 必ず add, and how is it different from きっと or 絶対に?

必ず: “without fail,” strong certainty/guarantee tone.
きっと: “surely/probably,” strong expectation but softer than 必ず; often used with と思います.
絶対に: “absolutely,” emphatic and sometimes stronger than 必ず; can sound forceful.

Where should 必ず go in the sentence?

Put it in the main clause it modifies: 新しい作戦なら、必ず成功すると思います. If you move 必ず earlier (e.g., 必ず、新しい作戦なら…), it scopes over “I definitely think …” rather than “It will definitely succeed,” which changes the meaning.

What does 作戦 mean here? Would 計画 or 方法 be different?

作戦 (strategy/tactics) often has a tactical, game-like, or military flavor. 計画 is a “plan/schedule” (neutral), 方法 is a “method/way,” and 戦略 is “strategy” at a higher, long-term level. Using 作戦 can sound more tactical or spirited.

Why use と思います at the end? Is it just “I think”?

Yes, but it also softens the assertion and is polite. Saying 成功します flatly can sound too certain or direct; 成功すると思います is a common, polite hedge.

How would the meaning change if I used は instead of なら (新しい作戦は必ず成功すると思います)?

は makes “the new strategy” the topic, asserting your belief about it, without the conditional nuance of “if it’s a new strategy.” なら frames it as a condition/contrast: “If (we go with) a new strategy (as opposed to other options)…”

Do I ever need だ before と when using と思います?

Yes, when the predicate before と is a noun or a na-adjective: 学生だと思います, 便利だと思います. With verbs and i-adjectives, no だ: 行くと思います, 高いと思います. Here we have a verb (成功する), so no だ.

Can I say 成功できる instead of 成功する?

成功できる focuses on ability/possibility (“can succeed”), while 成功する is a straightforward prediction (“will succeed”). With 必ず, 成功する sounds more like a firm prediction; 成功できる sounds like “it’s feasible.”

Is って思います okay in casual speech?

It appears in casual speech, but と思います is the default and sounds cleaner: 新しい作戦なら必ず成功すると思う. って is more colloquial and is often used when quoting someone else or softening: …んじゃないかなって思う.

Can I write ならば or のなら instead of なら?

ならば is a bit more formal/literary but fine: 新しい作戦ならば….
のなら (after clauses) adds a slightly explanatory tone: 新しい作戦にするのなら、必ず… (more “if it is the case that we choose a new strategy, then…”).

Do I need a comma after なら?

It’s optional but recommended for readability: 新しい作戦なら、必ず…. Japanese often inserts a comma after a long conditional/topic phrase.